Usc Housing Application 2011 2012: Fill & Download for Free

Congress has effectively made it illegal for Obama to do so.The following quotes are from the (erroneously) "infamous" NDAA of 2012. You may remember this one being referred to as a way to strip US citizens of their constitutional rights just for being a suspected terrorist. That is largely a matter of interpretation, but the courts seem to agree US citizens still have the same rights.The NDAA (National Defense Authorization Act) is a spending bill. But Congress tags a whole bunch of extra stuff in it all the time. For example (emphasis mine):"SEC. 1026. PROHIBITION ON USE OF FUNDS TO CONSTRUCT OR MODIFY FACILITIES IN THE UNITED STATES TO HOUSE DETAINEES TRANSFERRED FROM UNITED STATES NAVAL STATION, GUANTANAMO BAY, CUBA.(a) In General.--No amounts authorized to be appropriated or otherwise made available to the Department of Defense for fiscal year 2012 may be used to construct or modify any facility in the United States, its territories, or possessions to house any individual detained at Guantanamo for the purposes of detention or imprisonment in the custody or under the control of the Department of Defense unless authorized by Congress.(b) Exception.--The prohibition in subsection (a) shall not apply to any modification of facilities at United States Naval Station, Guantanamo Bay, Cuba.(c) Individual Detained at Guantanamo Defined.--In this section, the term ``individual detained at Guantanamo'' has the meaning given that term in section 1028(e)(2).(d) Repeal of Superseded Authority.--Section 1034 of the Ike Skelton National Defense Authorization Act for Fiscal Year 2011 (Public Law 111-383; 124 Stat. 4353) is amended by striking subsections (a), (b), and(c)."(Sec. 1026 of Public Law 112-81)and:"SEC. 1027. PROHIBITION ON THE USE OF FUNDS FOR THE TRANSFER OR RELEASE OF INDIVIDUALS DETAINED AT UNITED STATES NAVAL STATION, GUANTANAMO BAY, CUBA.None <<NOTE: Khalid Sheikh Mohammed.>> of the funds authorized to be appropriated by this Act for fiscal year 2012 may be used to transfer, release, or assist[[Page 125 STAT. 1567]]in the transfer or release to or within the United States, its territories, or possessions of Khalid Sheikh Mohammed or any other detainee who--(1) is not a United States citizen or a member of the Armed Forces of the United States; and(2) is or was held on or after January 20, 2009, at United States Naval Station, Guantanamo Bay, Cuba, by the Department of Defense."(Sec. 1027 of Public Law 112-81)Similar sections have been added to theNDAA of 2013 (read Title X, Subtitle D).There have been similar sections of each annual military spending bill since.Another section of the act from 2012 refers to the requirement that terrorism suspects captured "during the course of hostilities" or imprisoned on or after January 20, 2009 (coincidentally, George W. Bush's last day in office) be held in military custody. Since none were released during Bush's tenure, this refers to all of them.Oh, and Gitmo is the only place that's allowed anywhere near US soil. But that doesn't matter, because you cannot move them or release them anyway, without explicit permission on a case-by-case basis from Congress.Again, the emphasis is mine:"SEC. 1022. <<NOTE: 10 USC 801 note.>> MILITARY CUSTODY FOR FOREIGN AL-QAEDA TERRORISTS.(a) Custody Pending Disposition Under Law of War.-- (1) In general.--Except as provided in paragraph (4), the Armed Forces of the United States shall hold a person described in paragraph (2) who is captured in the course of hostilities authorized by the Authorization for Use of Military Force (Public Law 107-40) in military custody pending disposition under the law of war(2) Covered persons.--The <<NOTE: Applicability.>> requirement in paragraph (1) shall apply to any person whose detention is authorized under section 1021 who is determined--(A) to be a member of, or part of, al-Qaeda or an associated force that acts in coordination with or pursuant to the direction of al-Qaeda; and(B) to have participated in the course of planning or carrying out an attack or attempted attack against the United States or its coalition partners.(3) Disposition under law of war.--For purposes of this subsection, the disposition of a person under the law of war has the meaning given in section 1021(c), except that no transfer otherwise described in paragraph (4) of that section shall be made unless consistent with the requirements of section 1028.(4) Waiver for national security.--The President may waive the requirement of paragraph (1) if the President submits to Congress a certification in writing that such a waiver is in the national security interests of the United States.(b) Applicability to United States Citizens and Lawful Resident Aliens.--(1) United states citizens.--The requirement to detain a person in military custody under this section does not extend to citizens of the United States.(2) Lawful resident aliens.--The requirement to detain a person in military custody under this section does not extend to a lawful resident alien of the United States on the basis of conduct taking place within the United States, except to the extent permitted by the Constitution of the United States."(Public Law 112-81 Sec. 1022.)Congress basically has said that they don't trust Obama to make these decisions (even though these would normally fall under his exclusive purview), unless the President and the Secretary of Defense personally vouch for the prisoner and attest that this person, who has likely been held illegally during a non-official "war" for probably close to 14 years, will never commit an act of terrorism against the United States, or associate with other terrorism suspects, or give "aid or comfort" to any other suspect, and is therefore not a national security risk.If I were Pres. Obama, I would not agree to this either. I would quietly not mention it.Now... Why doesn't Obama veto these laws? He doesn't have a line item veto for this bill, and if he did, he wouldn't have time to use it. It usually arrives at his desk over two months late into the fiscal year that it funds. He literally cannot wait a second longer...Obama cannot veto this bill without defunding the entire US military.

it goes back to 1980’s when neoliberalism began and Russia relinquished Eastern Europe. There are several overlapping agendas in play.One of oldest tools of weak politicians is “Unity by Seperation”. This involves getting population scared of some threat (real or imagined) so they unite behind you for own perceived safety. The Middle East quickly became the new threat.Also they had not only dared to become financially independent in late 60’s and early 70’s they had returned serve on western profiteering on essential supply of oil. OPEC dared control supply to maximise profits just like we did with food to them. The West during this time actually created the trrrorist groups arming and training dissidents to try bring these countries down even. When that failed we tried invading even.Another shift in 1980’s was to stop meeting refugee obligations. Temporary protection visas designed to cover processing time became standard and Asylum became rare. Refugees started to accumulate in camps and internally displaced put in camps before they could cross border to falsely deflate numbers of refugees even though it exposed victims to much greater risks (Even Border camps not safe, I will includes verified statement at end of answer from one such victim).Coinciding with this shift in Western refugee policy began a propaganda campaign. Refugees began to be painted as faceless horde coming to take our jobs, wealth and wives. The word Refugee began to be replaced by economic migrant. Humanitarians assisting refugees became people smugglers and then interchangeable with Human traffickers (Yes there are many who profit transporting desperate refugees but majority or simple people doing what they can for no money) these profiteers also present helping Jews out of Germany in WWII and African Americans out of South in USA to escape slavery but history rightly proves they a minority just as they are now.The terms queue jumper and illegal entry were coined even though there is no queue and refugees have right of travel under article 31 of refugee convention to present themselves for Asylum.By time Syrian war began we had 20 million refugees in limbo and over 30 million internally displaced people Globally. Some have been in camps in Kenya and Pakistan over 30 years.So 30 years of propaganda against Middle East and refugees and the West had lost control of its dissident groups that had become terrorist groups we know today. Poor Syria had hit trifecta.What amazes me is half the population hasn't bought the propaganda and is trying to help. When you look at success of propaganda in last century it's a huge increase in public awareness and scrpticism in government and corporate media and significant progress in social awareness.This is a story from Kenyan Border camp verified by UNHCR staff and written by Aden with assistance from UNHCR staff and included in his Asylum applications. Hopefully you can see why more and more refugees choosing dangerous option of traveling.“NAME: ADEN MOHAMED SANTUR,SEX: MALE,NATIONALITY: SOMALI,D.O.BIRTH: 01-01-1984,P.O.BIRTH: BUALE-SOMALIA,MARITAL STATUS: MARRIED,RESIDENTIAL ADDRESS BLOCK B-1, HAGADERA, KENYA,LEGAL STATUS IN THE COUNTRY/RESIDENT: REFUGEE,TELL#: +254703282588,DATE: FEBRUARY 06, 2016.RE: DETAILS OF MY CASE HISTORYAs a child of six years in age I had lived with my parents and three siblings of mine “elder sister and two younger brothers” at my birth town “BUALE” when it happened that my home town came under attack from “USC” militia from Mogadishu area in one morning of mid, 1991 and there, my father and mother were shot and killed in front of my eyes and my siblings, whereby, my elder sister who was a child of eight at the time was sexually abused by the attackers consequent to that sad incident which left with me and my siblings a deep psychological scar that will never heal, my siblings and I along with others fleeing from our home town fled from there for our lives in that same day, heading towards Kenya as the nearest place that we could find a place we could live safety, via Buale-Afmadow-Dhobley, however, my siblings and I together with those we fled with arrived at Liboi border point of Kenya after a flight journey which took twenty-days, during which my siblings and would not have survived without the kind and humane assistance of some of those families we fled with, and there, my siblings and I were received as refugees by a team of UNHCR staff, the, we were shifted on board a lorries chartered by UNHCR from there to Hagadera refugee camp which was just set up in mid, 1992.Having arrived at this camp as un accompanied child and did not find any close relations of ours to seek assistance from upon our arrival, while, we were overwhelmed by the shock and the sorrow as well as they psychological trauma that the tragic loss of our beloved parents left with us, my siblings and I started to live in the most desperate, vulnerable and sorrowful situation in which we could not have survived if we did not get the kindness and humane assistance, constant parental advice and guidance from the mother of a family of a close neighbor, however, the desperation of my family’s situation had forced my elder sister to work for other families as housemaid while, at the same time doing the household activities of our family for her to earn something to support our desperate family’s livelihood while, she was only a child deeply traumatized by the sad memories of her past experience such as witnessing the horrific killing of both parents as well as the rape incident she experiences as a child of eight and even though, my sister’s sacrifice made possible for me and my younger brothers to survive and was able to go to school, it had a devastating effect on her health to such extent that I was forced not to join secondary school after completing my primary education course as I had to seek a job for me to be able to support my family as my elder sister who used to be the brad winner of the family had fallen ill and never recovered from and at last passed away sometime in 2010. More sadly, one of my younger brothers had passed away after a short illness in 2011.Nevertheless, as I was in such a deep sorrow and grief that the early deaths of my elder sister and younger brother caused to me, I came across my current spouse among other newly arrived refugees, while, I was working at the reception center of the camp as I was social worker, working for the implementing agencies based at my camp, however, I noticed that she was more sad and worrisome than all others, as such, I went to her and asked about her problems, so, she told me about her sad story informing me that she lost both of her parents to the civil war in childhood so, she lived with a family of her relations, then, as she grew up to a young lady her clan elders including her foster father decided to force her a marriage against her will and even worse, when she resisted against that proposed forced marriage, a group of the clan’s youth were assigned to make her to change her mind on the issue by the elders, so, as she insisted on her refusal to accept for that marriage, she was subjected to physical torture due to which she had to say that she was ready to avoid more pain, then, while they were getting prepared for the marriage she managed to escape from them with the help of some girls of her clan and other women of the neighbors and so, she arrived at this camp all alone, helpless and knowing not any one to turn to for assistance in all of the camps in Dadaab region in 2011.In this context, I told her about my tale, showing her that we had something in common, then, offered her to go with me and live with me and brother as our sister in the very hardships we lived in and she accepted my offer and started living with us, however, our sympathy to each other for our common childhood misfortunes had transformed in to intimate love to each other due to which we married each other in 2012.Nevertheless, soon after our marriage, death-threat calls/text messages from her clan’s members who traced her to the camp and came to know about marriage, against me and my spouse started reaching us, so, we had lived in great fear for quite a time before, the danger against us became more eminent than ever before when in one night of 3 March, 2014, armed men broke in to our house and though, I managed to escape from them, they had beaten my wife when she refused to go with them presumably to the intent of abducting her, then , they raped her, therefore, apart from the traumatic fear we have lived since then while, those threats are still reaching us, we have been facing sever segregatory acts against us from the rest of the community which made our life at the camp more painful and unendurable, whereby, neither me nor my spouse could go back home as our lives, freedom and human dignity will be in greater danger in back there as my home region is under the control of ALSHABAB terrorist group, where, my spouse’s life will never reserved by her own clan’s people if she go back there.In that sense, we do need urgent protection from this eminent danger against our lives in here in the country of our first asylum and in back home for us to be saved from a disastrous consequences I do hope that you kind and humane consideration of our situation will save our lives.NB: my younger brother “ABDIRAHMAN MOHAMED SANTUR” is the only person of my relation that I put on records for possible joining me there in the future.Yours sincerely ,Aden Mohamed Santur”

Quantum computing is computing using quantum-mechanical phenomena, such as superposition and entanglement.[1]A quantum computer is a device that performs quantum computing. Such a computer is different from binary digital electronic computers based on transistors. Whereas common digital computing requires that the data be encoded into binary digits (bits), each of which is always in one of two definite states (0 or 1), quantum computation uses quantum bits or qubits, which can be in superpositions of states. A quantum Turing machine is a theoretical model of such a computer and is also known as the universal quantum computer. The field of quantum computing was initiated by the work of Paul Benioff[2]and Yuri Manin in 1980,[3]Richard Feynman in 1982,[4]and David Deutsch in 1985.[5]As of 2018, the development of actual quantum computers is still in its infancy, but experiments have been carried out in which quantum computational operations were executed on a very small number of quantum bits.[6]Both practical and theoretical research continues, and many national governments and military agencies are funding quantum computing research in additional effort to develop quantum computers for civilian, business, trade, environmental and national security purposes, such as cryptanalysis.[7]Noisy devices with a small number of qubits have been developed by a number of companies, including IBM, Intel, and Google.[8]IBM has made 5-qubit and 16-qubit quantum computing devices available to the public for experiments via the cloud on the IBM Q Experience. D-Wave Systems has been developing their own version of a quantum computer that uses annealing.[9]Large-scale quantum computers would theoretically be able to solve certain problems much more quickly than any classical computers that use even the best currently known algorithms, like integer factorization using Shor's algorithm (which is a quantum algorithm) and the simulation of quantum many-body systems. There exist quantum algorithms, such as Simon's algorithm, that run faster than any possible probabilistic classical algorithm.[10]A classical computer could in principle (with exponential resources) simulate a quantum algorithm, as quantum computation does not violate the Church–Turing thesis.[11]:202On the other hand, quantum computers may be able to efficiently solve problems which are not practically feasible on classical computers.Contents1Basics2Principles of operation3Operation4Potential4.1Cryptography4.2Quantum search4.3Quantum simulation4.4Quantum annealing and adiabatic optimisation4.5Solving linear equations4.6Quantum supremacy5Obstacles5.1Quantum decoherence6Developments6.1Quantum computing models6.2Physical realizations6.3Timeline7Relation to computational complexity theory8See also9References10Further reading11External linksBasics[edit]A classical computer has a memory made up of bits, where each bit is represented by either a one or a zero. A quantum computer, on the other hand, maintains a sequence of qubits, which can represent a one, a zero, or any quantum superposition of those two qubit states;[11]:13–16a pair of qubits can be in any quantum superposition of 4 states,[11]:16and three qubits in any superposition of 8 states. In general, a quantum computer with [math]{\displaystyle n}[/math] qubits can be in an arbitrary superposition of up to [math]{\displaystyle 2^{n}}[/math] different states simultaneously.[11]:17(This compares to a normal computer that can only be in one of these [math]{\displaystyle 2^{n}}[/math] states at any one time).A quantum computer operates on its qubits using quantum gates and measurement (which also alters the observed state). An algorithm is composed of a fixed sequence of quantum logic gates and a problem is encoded by setting the initial values of the qubits, similar to how a classical computer works. The calculation usually ends with a measurement, collapsing the system of qubits into one of the [math]{\displaystyle 2^{n}}[/math] eigenstates, where each qubit is zero or one, decomposing into a classical state. The outcome can, therefore, be at most [math]{\displaystyle n}[/math] classical bits of information (or, if the algorithm did not end with a measurement, the result is an unobserved quantum state).Quantum algorithms are often probabilistic, in that they provide the correct solution only with a certain known probability.[12]Note that the term non-deterministic computing must not be used in that case to mean probabilistic (computing) because the term non-deterministic has a different meaning in computer science.An example of an implementation of qubits of a quantum computer could start with the use of particles with two spin states: "down" and "up" (typically written [math]{\displaystyle |{\downarrow }\rangle }[/math] and [math]{\displaystyle |{\uparrow }\rangle }[/math], or [math]{\displaystyle |0{\rangle }}[/math] and [math]{\displaystyle |1{\rangle }}[/math]). This is true because any such system can be mapped onto an effective spin-1/2 system.Principles of operation[edit]This section includes a list of references, but its sources remain unclear because it has insufficient inline citations.Please help to improve this section by introducing more precise citations.(February 2018)(Learn how and when to remove this template message)A quantum computer with a given number of qubits is fundamentally different from a classical computer composed of the same number of classical bits. For example, representing the state of an n-qubit system on a classical computer requires the storage of 2ncomplex coefficients, while to characterize the state of a classical n-bit system it is sufficient to provide the values of the n bits, that is, only n numbers. Although this fact may seem to indicate that qubits can hold exponentially more information than their classical counterparts, care must be taken not to overlook the fact that the qubits are only in a probabilistic superposition of all of their states. This means that when the final state of the qubits is measured, they will only be found in one of the possible configurations they were in before the measurement. It is generally incorrect to think of a system of qubits as being in one particular state before the measurement. Since the fact that they were in a superposition of states before the measurement was made directly affects the possible outcomes of the computation.Qubits are made up of controlled particles and the means of control (e.g. devices that trap particles and switch them from one state to another).[13]To better understand this point, consider a classical computer that operates on a three-bit register. If the exact state of the register at a given time is not known, it can be described as a probability distribution over the [math]{\displaystyle 2^{3}=8}[/math] different three-bit strings000, 001, 010, 011, 100, 101, 110,and111. If there is no uncertainty over its state, then it is in exactly one of these states with probability 1. However, if it is a probabilistic computer, then there is a possibility of it being in any one of a number of different states.The state of a three-qubit quantum computer is similarly described by an eight-dimensional vector [math]{\displaystyle (a_{0},a_{1},a_{2},a_{3},a_{4},a_{5},a_{6},a_{7})}[/math](or a one dimensional vector with each vector node holding the amplitude and the state as the bit string of qubits). Here, however, the coefficients [math]{\displaystyle a_{i}}[/math] are complex numbers, and it is the sum of the squares of the coefficients' absolute values, [math]{\displaystyle \sum _{i}|a_{i}|^{2}}[/math], that must equal 1. For each [math]{\displaystyle i}[/math], the absolute value squared [math]{\displaystyle \left|a_{i}\right|^{2}}[/math] gives the probability of the system being found in the [math]{\displaystyle i}[/math]-th state after a measurement. However, because a complex number encodes not just a magnitude but also a direction in the complex plane, the phase difference between any two coefficients (states) represents a meaningful parameter. This is a fundamental difference between quantum computing and probabilistic classical computing.[14]If you measure the three qubits, you will observe a three-bit string. The probability of measuring a given string is the squared magnitude of that string's coefficient (i.e., the probability of measuring000= [math]{\displaystyle |a_{0}|^{2}}[/math], the probability of measuring001= [math]{\displaystyle |a_{1}|^{2}}[/math], etc.). Thus, measuring a quantum state described by complex coefficients [math]{\displaystyle (a_{0},a_{1},a_{2},a_{3},a_{4},a_{5},a_{6},a_{7})}[/math] gives the classical probability distribution [math]{\displaystyle (|a_{0}|^{2},|a_{1}|^{2},|a_{2}|^{2},|a_{3}|^{2},|a_{4}|^{2},|a_{5}|^{2},|a_{6}|^{2},|a_{7}|^{2})}[/math] and we say that the quantum state "collapses" to a classical state as a result of making the measurement.An eight-dimensional vector can be specified in many different ways depending on what basis is chosen for the space. The basis of bit strings (e.g.,000,001, …,111) is known as the computational basis. Other possible bases are unit-length, orthogonal vectors and the eigenvectors of the Pauli-x operator. Ket notation is often used to make the choice of basis explicit. For example, the state [math]{\displaystyle (a_{0},a_{1},a_{2},a_{3},a_{4},a_{5},a_{6},a_{7})}[/math] in the computational basis can be written as:[math]{\displaystyle a_{0}\,|000\rangle +a_{1}\,|001\rangle +a_{2}\,|010\rangle +a_{3}\,|011\rangle +a_{4}\,|100\rangle +a_{5}\,|101\rangle +a_{6}\,|110\rangle +a_{7}\,|111\rangle }[/math]where, e.g., [math]{\displaystyle |010\rangle =\left(0,0,1,0,0,0,0,0\right)}[/math]The computational basis for a single qubit (two dimensions) is [math]{\displaystyle |0\rangle =\left(1,0\right)}[/math] and [math]{\displaystyle |1\rangle =\left(0,1\right)}[/math].Using the eigenvectors of the Pauli-x operator, a single qubit is [math]{\displaystyle |+\rangle ={\tfrac {1}{\sqrt {2}}}\left(1,1\right)}[/math] and [math]{\displaystyle |-\rangle ={\tfrac {1}{\sqrt {2}}}\left(1,-1\right)}[/math].Operation[edit]This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed.(February 2018)(Learn how and when to remove this template message)Unsolved problem in physics:Is a universal quantum computer sufficient to efficiently simulate an arbitrary physical system?(more unsolved problems in physics)While a classical 3-bit state and a quantum 3-qubit state are each eight-dimensional vectors, they are manipulated quite differently for classical or quantum computation. For computing in either case, the system must be initialized, for example into the all-zeros string, [math]{\displaystyle |000\rangle }[/math], corresponding to the vector (1,0,0,0,0,0,0,0). In classical randomized computation, the system evolves according to the application of stochastic matrices, which preserve that the probabilities add up to one (i.e., preserve the L1 norm). In quantum computation, on the other hand, allowed operations are unitary matrices, which are effectively rotations (they preserve that the sum of the squares add up to one, the Euclidean or L2 norm). (Exactly what unitaries can be applied depend on the physics of the quantum device.) Consequently, since rotations can be undone by rotating backward, quantum computations are reversible. (Technically, quantum operations can be probabilistic combinations of unitaries, so quantum computation really does generalize classical computation. See quantum circuit for a more precise formulation.)Finally, upon termination of the algorithm, the result needs to be read off. In the case of a classical computer, we sample from the probability distribution on the three-bit register to obtain one definite three-bit string, say 000. Quantum mechanically, one measures the three-qubit state, which is equivalent to collapsing the quantum state down to a classical distribution (with the coefficients in the classical state being the squared magnitudes of the coefficients for the quantum state, as described above), followed by sampling from that distribution. This destroys the original quantum state. Many algorithms will only give the correct answer with a certain probability. However, by repeatedly initializing, running and measuring the quantum computer's results, the probability of getting the correct answer can be increased. In contrast, counterfactual quantum computation allows the correct answer to be inferred when the quantum computer is not actually running in a technical sense, though earlier initialization and frequent measurements are part of the counterfactual computation protocol.For more details on the sequences of operations used for various quantum algorithms, see universal quantum computer, Shor's algorithm, Grover's algorithm, Deutsch–Jozsa algorithm, amplitude amplification, quantum Fourier transform, quantum gate, quantum adiabatic algorithm and quantum error correction.Potential[edit]Cryptography[edit]Integer factorization, which underpins the security of public key cryptographic systems, is believed to be computationally infeasible with an ordinary computer for large integers if they are the product of few prime numbers (e.g., products of two 300-digit primes).[15]By comparison, a quantum computer could efficiently solve this problem using Shor's algorithm to find its factors. This ability would allow a quantum computer to break many of the cryptographic systems in use today, in the sense that there would be a polynomial time (in the number of digits of the integer) algorithm for solving the problem. In particular, most of the popular public key ciphers are based on the difficulty of factoring integers or the discrete logarithm problem, both of which can be solved by Shor's algorithm. In particular, the RSA, Diffie–Hellman, and elliptic curve Diffie–Hellman algorithms could be broken. These are used to protect secure Web pages, encrypted email, and many other types of data. Breaking these would have significant ramifications for electronic privacy and security.However, other cryptographic algorithms do not appear to be broken by those algorithms.[16][17]Some public-key algorithms are based on problems other than the integer factorization and discrete logarithm problems to which Shor's algorithm applies, like the McEliece cryptosystem based on a problem in coding theory.[16][18]Lattice-based cryptosystems are also not known to be broken by quantum computers, and finding a polynomial time algorithm for solving the dihedral hidden subgroup problem, which would break many lattice based cryptosystems, is a well-studied open problem.[19]It has been proven that applying Grover's algorithm to break a symmetric (secret key) algorithm by brute force requires time equal to roughly 2n/2invocations of the underlying cryptographic algorithm, compared with roughly 2nin the classical case,[20]meaning that symmetric key lengths are effectively halved: AES-256 would have the same security against an attack using Grover's algorithm that AES-128 has against classical brute-force search (see Key size). Quantum cryptography could potentially fulfill some of the functions of public key cryptography. Quantum-based cryptographic systems could ,therefore, be more secure than traditional systems against quantum hacking.[21]Quantum search[edit]Besides factorization and discrete logarithms, quantum algorithms offering a more than polynomial speedup over the best known classical algorithm have been found for several problems,[22]including the simulation of quantum physical processes from chemistry and solid state physics, the approximation of Jones polynomials, and solving Pell's equation. No mathematical proof has been found that shows that an equally fast classical algorithm cannot be discovered, although this is considered unlikely.[23]For some problems, quantum computers offer a polynomial speedup. The most well-known example of this is quantum database search, which can be solved by Grover's algorithm using quadratically fewer queries to the database than that are required by classical algorithms. In this case, the advantage is not only provable but also optimal, it has been shown that Grover's algorithm gives the maximal possible probability of finding the desired element for any number of oracle lookups. Several other examples of provable quantum speedups for query problems have subsequently been discovered, such as for finding collisions in two-to-one functions and evaluating NAND trees.Problems that can be addressed with Grover's algorithm have the following properties:There is no searchable structure in the collection of possible answers,The number of possible answers to check is the same as the number of inputs to the algorithm, andThere exists a boolean function which evaluates each input and determines whether it is the correct answerFor problems with all these properties, the running time of Grover's algorithm on a quantum computer will scale as the square root of the number of inputs (or elements in the database), as opposed to the linear scaling of classical algorithms. A general class of problems to which Grover's algorithm can be applied[24]is Boolean satisfiability problem. In this instance, the database through which the algorithm is iterating is that of all possible answers. An example (and possible) application of this is a password cracker that attempts to guess the password or secret key for an encrypted file or system. Symmetric ciphers such as Triple DES and AES are particularly vulnerable to this kind of attack.[25]This application of quantum computing is a major interest of government agencies.[26]Quantum simulation[edit]Since chemistry and nanotechnology rely on understanding quantum systems, and such systems are impossible to simulate in an efficient manner classically, many believe quantum simulation will be one of the most important applications of quantum computing.[27]Quantum simulation could also be used to simulate the behavior of atoms and particles at unusual conditions such as the reactions inside a collider.[28]Quantum annealing and adiabatic optimisation[edit]Adiabatic quantum computation relies on the adiabatic theorem to undertake calculations. A system is placed in the ground state for a simple Hamiltonian, which is slowly evolved to a more complicated Hamiltonian whose ground state represents the solution to the problem in question. The adiabatic theorem states that if the evolution is slow enough the system will stay in its ground state at all times through the process.Solving linear equations[edit]The Quantum algorithm for linear systems of equations or "HHL Algorithm", named after its discoverers Harrow, Hassidim, and Lloyd, is expected to provide speedup over classical counterparts.[29]Quantum supremacy[edit]John Preskill has introduced the term quantum supremacy to refer to the hypothetical speedup advantage that a quantum computer would have over a classical computer in a certain field.[30]Google announced in 2017 that it expected to achieve quantum supremacy by the end of the year, and IBM says that the best classical computers will be beaten on some task within about five years.[31]Quantum supremacy has not been achieved yet, and skeptics like Gil Kalai doubt that it will ever be.[32][33]Bill Unruh doubted the practicality of quantum computers in a paper published back in 1994.[34]Paul Davies pointed out that a 400-qubit computer would even come into conflict with the cosmological information bound implied by the holographic principle.[35]Those such as Roger Schlafly have pointed out that the claimed theoretical benefits of quantum computing go beyond the proven theory of quantum mechanics and imply non-standard interpretations, such as the many-worlds interpretation and negative probabilities. Schlafly maintains that the Born rule is just "metaphysical fluff" and that quantum mechanics does not rely on probability any more than other branches of science but simply calculates the expected values of observables. He also points out that arguments about Turing complexity cannot be run backwards.[36][37][38]Those who prefer Bayesian interpretations of quantum mechanics have questioned the physical nature of the mathematical abstractions employed.[39]Obstacles[edit]There are a number of technical challenges in building a large-scale quantum computer, and thus far quantum computers have yet to solve a problem faster than a classical computer. David DiVincenzo, of IBM, listed the following requirements for a practical quantum computer:[40]scalable physically to increase the number of qubits;qubits that can be initialized to arbitrary values;quantum gates that are faster than decoherence time;universal gate set;qubits that can be read easily.Quantum decoherence[edit]Main article: Quantum decoherenceOne of the greatest challenges is controlling or removing quantum decoherence. This usually means isolating the system from its environment as interactions with the external world cause the system to decohere. However, other sources of decoherence also exist. Examples include the quantum gates, and the lattice vibrations and background thermonuclear spin of the physical system used to implement the qubits. Decoherence is irreversible, as it is effectively non-unitary, and is usually something that should be highly controlled, if not avoided. Decoherence times for candidate systems in particular, the transverse relaxation time T2(for NMR and MRItechnology, also called the dephasing time), typically range between nanoseconds and seconds at low temperature.[14]Currently, some quantum computers require their qubits to be cooled to 20 millikelvins in order to prevent significant decoherence.[41]As a result, time-consuming tasks may render some quantum algorithms inoperable, as maintaining the state of qubits for a long enough duration will eventually corrupt the superpositions.[42]These issues are more difficult for optical approaches as the timescales are orders of magnitude shorter and an often-cited approach to overcoming them is optical pulse shaping. Error rates are typically proportional to the ratio of operating time to decoherence time, hence any operation must be completed much more quickly than the decoherence time.As described in the Quantum threshold theorem, if the error rate is small enough, it is thought to be possible to use quantum error correction to suppress errors and decoherence. This allows the total calculation time to be longer than the decoherence time if the error correction scheme can correct errors faster than decoherence introduces them. An often cited figure for the required error rate in each gate for fault-tolerant computation is 10−3, assuming the noise is depolarizing.Meeting this scalability condition is possible for a wide range of systems. However, the use of error correction brings with it the cost of a greatly increased number of required qubits. The number required to factor integers using Shor's algorithm is still polynomial, and thought to be between L and L2, where L is the number of qubits in the number to be factored; error correction algorithms would inflate this figure by an additional factor of L. For a 1000-bit number, this implies a need for about 104bits without error correction.[43]With error correction, the figure would rise to about 107bits. Computation time is about L2or about 107steps and at 1 MHz, about 10 seconds.A very different approach to the stability-decoherence problem is to create a topological quantum computer with anyons, quasi-particles used as threads and relying on braid theory to form stable logic gates.[44][45]Developments[edit]Quantum computing models[edit]There are a number of quantum computing models, distinguished by the basic elements in which the computation is decomposed. The four main models of practical importance are:Quantum gate array (computation decomposed into a sequence of few-qubit quantum gates)One-way quantum computer (computation decomposed into a sequence of one-qubit measurements applied to a highly entangled initial state or cluster state)Adiabatic quantum computer, based on quantum annealing (computation decomposed into a slow continuous transformation of an initial Hamiltonian into a final Hamiltonian, whose ground states contain the solution)[46]Topological quantum computer[47] (computation decomposed into the braiding of anyons in a 2D lattice)The quantum Turing machine is theoretically important but the direct implementation of this model is not pursued. All four models of computation have been shown to be equivalent; each can simulate the other with no more than polynomial overhead.Physical realizations[edit]For physically implementing a quantum computer, many different candidates are being pursued, among them (distinguished by the physical system used to realize the qubits):Superconducting quantum computing[48][49] (qubit implemented by the state of small superconducting circuits (Josephson junctions))Trapped ion quantum computer (qubit implemented by the internal state of trapped ions)Optical lattices (qubit implemented by internal states of neutral atoms trapped in an optical lattice)Quantum dot computer, spin-based (e.g. the Loss-DiVincenzo quantum computer[50]) (qubit given by the spin states of trapped electrons)Quantum dot computer, spatial-based (qubit given by electron position in double quantum dot)[51]Coupled Quantum Wire (qubit implemented by a pair of Quantum Wires coupled by a Quantum Point Contact)[52][53][54]Nuclear magnetic resonance quantum computer (NMRQC) implemented with the nuclear magnetic resonance of molecules in solution, where qubits are provided by nuclear spins within the dissolved molecule and probed with radio wavesSolid-state NMR Kane quantum computers (qubit realized by the nuclear spin state of phosphorus donors in silicon)Electrons-on-helium quantum computers (qubit is the electron spin)Cavity quantum electrodynamics (CQED) (qubit provided by the internal state of trapped atoms coupled to high-finesse cavities)Molecular magnet[55] (qubit given by spin states)Fullerene-based ESR quantum computer (qubit based on the electronic spin of atoms or molecules encased in fullerenes)Linear optical quantum computer (qubits realized by processing states of different modes of light through linear elements e.g. mirrors, beam splitters and phase shifters)[56]Diamond-based quantum computer[57][58][59] (qubit realized by the electronic or nuclear spin of nitrogen-vacancy centers in diamond)Bose-Einstein condensate-based quantum computer[60]Transistor-based quantum computer – string quantum computers with entrainment of positive holes using an electrostatic trapRare-earth-metal-ion-doped inorganic crystal based quantum computers[61][62] (qubit realized by the internal electronic state of dopants in optical fibers)Metallic-like carbon nanospheres based quantum computers[63]A large number of candidates demonstrates that the topic, in spite of rapid progress, is still in its infancy. There is also a vast amount of flexibility.Timeline[edit]Main article: Timeline of quantum computingIn 1959 Richard Feynman in his lecture "There's Plenty of Room at the Bottom" states the possibility of using quantum effects for computation.In 1980 Paul Benioff described quantum mechanical Hamiltonian models of computers[64]and the Russian mathematician Yuri Manin motivated the development of quantum computers.[65]In 1981, at a conference co-organized by MIT and IBM, physicist Richard Feynman urged the world to build a quantum computer. He said, "Nature isn't classical, dammit, and if you want to make a simulation of nature, you'd better make it quantum mechanical, and by golly, it's a wonderful problem because it doesn't look so easy."[66]In 1984, BB84 is published, the world's first quantum cryptography protocol by IBM scientists Charles Bennett and Gilles Brassard.In 1993, an international group of six scientists, including Charles Bennett, showed that perfect quantum teleportation is possible[67]in principle, but only if the original is destroyed.In 1994 Peter Shor, at AT&T's Bell Labs discovered an important quantum algorithm, which allows a quantum computer to factor large integers exponentially much faster than the best known classical algorithm. Shor's algorithm can theoretically break many of the public-key cryptosystems in use today.[68]Its invention sparked a tremendous interest in quantum computers.In 1996, The DiVincenzo's criteria are published which is a list of conditions that are necessary for constructing a quantum computer proposed by the theoretical physicist David P. DiVincenzo in his 2000 paper "The Physical Implementation of Quantum Computation".In 2001, researchers demonstrated Shor's algorithm to factor 15 using a 7-qubit NMR computer.[69]In 2005, researchers at the University of Michigan built a semiconductor chip ion trap. Such devices from standard lithography may point the way to scalable quantum computing.[70]In 2009, researchers at Yale University created the first solid-state quantum processor. The two-qubit superconducting chip had artificial atom qubits made of a billion aluminum atoms that acted like a single atom that could occupy two states.[71][72]A team at the University of Bristol also created a silicon chip based on quantum optics, able to run Shor's algorithm.[73]Further developments were made in 2010.[74]Springer publishes a journal (Quantum Information Processing) devoted to the subject.[75]In February 2010, Digital Combinational Circuits like an adder, subtractor etc. are designed with the help of Symmetric Functions organized from different quantum gates.[76][77]In April 2011, a team of scientists from Australia and Japan made a breakthrough in quantum teleportation. They successfully transferred a complex set of quantum data with full transmission integrity, without affecting the qubits' superpositions.[78][79]Photograph of a chip constructed by D-Wave Systems Inc. Mounted and wire-bonded in a sample holder. The D-Wave processor is designed to use 128 superconducting logic elements that exhibit controllable and tunable coupling to perform operations.In 2011, D-Wave Systems announced the first commercial quantum annealer, the D-Wave One, claiming a 128 qubit processor. On May 25, 2011, Lockheed Martin agreed to purchase a D-Wave One system.[80]Lockheed and the University of Southern California (USC) will house the D-Wave One at the newly formed USC Lockheed Martin Quantum Computing Center.[81]D-Wave's engineers designed the chips with an empirical approach, focusing on solving particular problems. Investors liked this more than academics, who said D-Wave had not demonstrated they really had a quantum computer. Criticism softened after a D-Wave paper in Nature, that proved the chips have some quantum properties.[82][83]Two published papers have suggested that the D-Wave machine's operation can be explained classically, rather than requiring quantum models.[84][85]Later work showed that classical models are insufficient when all available data is considered.[86]Experts remain divided on the ultimate classification of the D-Wave systems though their quantum behavior was established concretely with a demonstration of entanglement.[87]During the same year, researchers at the University of Bristol created an all-bulk optics system that ran a version of Shor's algorithm to successfully factor 21.[88]In September 2011 researchers proved quantum computers can be made with a Von Neumann architecture (separation of RAM).[89]In November 2011 researchers factorized 143 using 4 qubits.[90]In February 2012 IBM scientists said that they had made several breakthroughs in quantum computing with superconducting integrated circuits.[91]In April 2012 a multinational team of researchers from the University of Southern California, Delft University of Technology, the Iowa State University of Science and Technology, and the University of California, Santa Barbara, constructed a two-qubit quantum computer on a doped diamond crystal that can easily be scaled up and is functional at room temperature. Two logical qubit directions of electron spin and nitrogen kernels spin were used, with microwave impulses. This computer ran Grover's algorithm generating the right answer from the first try in 95% of cases.[92]In September 2012, Australian researchers at the University of New South Wales said the world's first quantum computer was just 5 to 10 years away, after announcing a global breakthrough enabling the manufacture of its memory building blocks. A research team led by Australian engineers created the first working qubit based on a single atom in silicon, invoking the same technological platform that forms the building blocks of modern-day computers.[93][94]In October 2012, Nobel Prizes were presented to David J. Wineland and Serge Haroche for their basic work on understanding the quantum world, which may help make quantum computing possible.[95][96]In November 2012, the first quantum teleportation from one macroscopic object to another was reported by scientists at the University of Science and Technology of China in Hefei.[97][98]In December 2012, the first dedicated quantum computing software company, 1QBit was founded in Vancouver, BC.[99]1QBit is the first company to focus exclusively on commercializing software applications for commercially available quantum computers, including the D-Wave Two. 1QBit's research demonstrated the ability of superconducting quantum annealing processors to solve real-world problems.[100]In February 2013, a new technique, boson sampling, was reported by two groups using photons in an optical lattice that is not a universal quantum computer but may be good enough for practical problems. Science Feb 15, 2013In May 2013, Google announced that it was launching the Quantum Artificial Intelligence Lab, hosted by NASA's Ames Research Center, with a 512-qubit D-Wave quantum computer. The USRA (Universities Space Research Association) will invite researchers to share time on it with the goal of studying quantum computing for machine learning.[101]Google added that they had "already developed some quantum machine learning algorithms" and had "learned some useful principles", such as that "best results" come from "mixing quantum and classical computing".[101]In early 2014 it was reported, based on documents provided by former NSA contractor Edward Snowden, that the U.S. National Security Agency (NSA) is running a $79.7 million research program (titled "Penetrating Hard Targets") to develop a quantum computer capable of breaking vulnerable encryption.[102]In 2014, a group of researchers from ETH Zürich, USC, Google ,and Microsoft reported a definition of quantum speedup, and were not able to measure quantum speedup with the D-Wave Two device, but did not explicitly rule it out.[103][104]In 2014, researchers at University of New South Wales used silicon as a protectant shell around qubits, making them more accurate, increasing the length of time they will hold information, and possibly making quantum computers easier to build.[105]In April 2015 IBM scientists claimed two critical advances towards the realization of a practical quantum computer. They claimed the ability to detect and measure both kinds of quantum errors simultaneously, as well as a new, square quantum bit circuit design that could scale to larger dimensions.[106]In October 2015, QuTech successfully conducts the Loophole-free Bell inequality violation test using electron spins separated by 1.3 kilometres.[107]In October 2015 researchers at the University of New South Wales built a quantum logic gate in silicon for the first time.[108]In December 2015 NASA publicly displayed the world's first fully operational $15-million quantum computer made by the Canadian company D-Wave at the Quantum Artificial Intelligence Laboratory at its Ames Research Center in California's Moffett Field. The device was purchased in 2013 via a partnership with Google and Universities Space Research Association. The presence and use of quantum effects in the D-Wave quantum processing unit is more widely accepted.[109]In some tests, it can be shown that the D-Wave quantum annealing processor outperforms Selby’s algorithm.[110]Only two of this computer have been made so far.In May 2016, IBM Research announced[111]that for the first time ever it is making quantum computing available to members of the public via the cloud, who can access and run experiments on IBM’s quantum processor. The service is called the IBM Quantum Experience. The quantum processor is composed of five superconducting qubits and is housed at the IBM T. J. Watson Research Center in New York.In August 2016, scientists at the University of Maryland successfully built the first reprogrammable quantum computer.[112]In October 2016 Basel University described a variant of the electron-hole based quantum computer, which instead of manipulating electron spins uses electron holes in a semiconductor at low (mK) temperatures which are a lot less vulnerable to decoherence. This has been dubbed the "positronic" quantum computer as the quasi-particle behaves like it has a positive electrical charge.[113]In March 2017, IBM announced an industry-first initiative to build commercially available universal quantum computing systems called IBM Q. The company also released a new API (Application Program Interface) for the IBM Quantum Experience that enables developers and programmers to begin building interfaces between its existing five quantum bit (qubit) cloud-based quantum computer and classical computers, without needing a deep background in quantum physics.In May 2017, IBM announced[114]that it has successfully built and tested its most powerful universal quantum computing processors. The first is a 16 qubit processor that will allow for more complex experimentation than the previously available 5 qubit processor. The second is IBM's first prototype commercial processor with 17 qubits and leverages significant materials, device, and architecture improvements to make it the most powerful quantum processor created to date by IBM.In July 2017, a group of U.S. researchers announced a quantum simulator with 51 qubits. The announcement was made by Mikhail Lukin of Harvard University at the International Conference on Quantum Technologies in Moscow.[115]A quantum simulator differs from a computer. Lukin’s simulator was designed to solve one equation. Solving a different equation would require building a new system. A computer can solve many different equations.In September 2017, IBM Research scientists use a 7 qubit device to model the largest molecule,[116]Beryllium hydride, ever by a quantum computer. The results were published as the cover story in the peer-reviewed journal Nature.In October 2017, IBM Research scientists successfully "broke the 49-qubit simulation barrier" and simulated 49- and 56-qubit short-depth circuits, using the Lawrence Livermore National Laboratory's Vulcan supercomputer, and the University of Illinois' Cyclops Tensor Framework (originally developed at the University of California). The results were published in arxiv.[117]In November 2017, the University of Sydney research team in Australia successfully made a microwave circulator, an important quantum computer part, 1000 times smaller than a conventional circulator by using topological insulators to slow down the speed of light in a material.[118]In December 2017, IBM announced[119]its first IBM Q Network clients. The companies, universities, and labs to explore practical quantum applications, using IBM Q 20 qubit commercial systems, for business and science include: JPMorgan Chase, Daimler AG, Samsung, JSR Corporation, Barclays, Hitachi Metals, Honda, Nagase, Keio University, Oak Ridge National Lab, Oxford University and University of Melbourne.In December 2017, Microsoft released a preview version of a "Quantum Development Kit".[120]It includes a programming language, Q#, which can be used to write programs that are run on an emulated quantum computer.In 2017 D-Wave reported to start selling a 2000 qubit quantum computer.[121]In late 2017 and early 2018 IBM,[122]Intel,[123]and Google[124]each reported testing quantum processors containing 50, 49, and 72 qubits, respectively, all realized using superconducting circuits. By number of qubits, these circuits are approaching the range in which simulating their quantum dynamics is expected to become prohibitive on classical computers, although it has been argued that further improvements in error rates are needed to put classical simulation out of reach.[125]In February 2018, scientists reported, for the first time, the discovery of a new form of light, which may involve polaritons, that could be useful in the development of quantum computers.[126][127]In February 2018, QuTech reported successfully testing a silicon-based two-spin-qubits quantum processor.[128]In June 2018, Intel begins testing silicon-based spin-qubit processor, manufactured in the company's D1D Fab in Oregon.[129]In July 2018, a team led by the University of Sydney has achieved the world's first multi-qubit demonstration of a quantum chemistry calculation performed on a system of trapped ions, one of the leading hardware platforms in the race to develop a universal quantum computer.[130]Relation to computational complexity theory[edit]Main article: Quantum complexity theoryThe suspected relationship of BQP to other problem spaces.[131]The class of problems that can be efficiently solved by quantum computers is called BQP, for "bounded error, quantum, polynomial time". Quantum computers only run probabilistic algorithms, so BQP on quantum computers is the counterpart of BPP ("bounded error, probabilistic, polynomial time") on classical computers. It is defined as the set of problems solvable with a polynomial-time algorithm, whose probability of error is bounded away from one half.[132]A quantum computer is said to "solve" a problem if, for every instance, its answer will be right with high probability. If that solution runs in polynomial time, then that problem is in BQP.BQP is contained in the complexity class #P (or more precisely in the associated class of decision problems P#P),[133]which is a subclass of PSPACE.BQP is suspected to be disjoint from NP-complete and a strict superset of P, but that is not known. Both integer factorizationand discrete log are in BQP. Both of these problems are NP problems suspected to be outside BPP, and hence outside P. Both are suspected to not be NP-complete. There is a common misconception that quantum computers can solve NP-complete problems in polynomial time. That is not known to be true, and is generally suspected to be false.[133]The capacity of a quantum computer to accelerate classical algorithms has rigid limits—upper bounds of quantum computation's complexity. The overwhelming part of classical calculations cannot be accelerated on a quantum computer.[134]A similar fact takes place for particular computational tasks, like the search problem, for which Grover's algorithm is optimal.[135]Bohmian Mechanics is a non-local hidden variable interpretation of quantum mechanics. It has been shown that a non-local hidden variable quantum computer could implement a search of an N-item database at most in [math]{\displaystyle O({\sqrt[{3}]{N}})}[/math] steps. This is slightly faster than the [math]{\displaystyle O({\sqrt {N}})}[/math] steps taken by Grover's algorithm. Neither search method will allow quantum computers to solve NP-Complete problems in polynomial time.[136]Although quantum computers may be faster than classical computers for some problem types, those described above cannot solve any problem that classical computers cannot already solve. A Turing machine can simulate these quantum computers, so such a quantum computer could never solve an undecidable problemlike the halting problem. The existence of "standard" quantum computers does not disprove the Church–Turing thesis.[137]It has been speculated that theories of quantum gravity, such as M-theory or loop quantum gravity, may allow even faster computers to be built. Currently, defining computation in such theories is an open problem due to the problem of time, i.e., there currently exists no obvious way to describe what it means for an observer to submit input to a computer and later receive output.[138][80]