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{{Tone|date=November 2019}}

{{Tone|date=November 2019}}

'''Quantum computing''' is the use of [[quantum physics|quantum]] phenomena such as [[quantum superposition|superposition]] and [[quantum entanglement|entanglement]] to perform [[computation]]. Computers that perform quantum computations are known as '''quantum computers'''.<ref name=2018Report>{{cite book | title=Quantum Computing : Progress and Prospects (2018) | page= I-5 | publisher=National Academies Press | editor-last1 = Grumbling | editor-first1 = Emily | editor-last2 = Horowitz | editor-first2 = Mark | author= The National Academies of Sciences, Engineering, and Medicine|location=Washington, DC | year=2019 | doi=10.17226/25196|isbn=978-0-309-47969-1 | oclc=1081001288 }}</ref>{{rp|I-5}} Quantum computers are believed to be able to solve certain [[computational problem]]s, such as [[integer factorization]] (which underlies [[RSA encryption]]), substantially faster than classical computers. The study of quantum computing is a subfield of [[quantum information science]].

'''Quantum computing''' is the use of [[quantum physics|quantum]] phenomena such as [[quantum superposition|superposition]] and [[quantum entanglement|entanglement]] to perform [[computation]]. Computers that perform quantum computations are known as '''quantum computers'''.{{rp|I-5}} Quantum computers are believed to be able to solve certain [[computational problem]]s, such as [[integer factorization]] (which underlies [[RSA encryption]]), substantially faster than classical computers. The study of quantum computing is a subfield of [[quantum information science]].

Quantum computing is the use of quantum phenomena such as superposition and entanglement to perform computation. Computers that perform quantum computations are known as quantum computers. Quantum computers are believed to be able to solve certain computational problems, such as integer factorization (which underlies RSA encryption), substantially faster than classical computers. The study of quantum computing is a subfield of quantum information science.

Quantum computing is the use of quantum phenomena such as superposition and entanglement to perform computation. Computers that perform quantum computations are known as quantum computers. Quantum computers are believed to be able to solve certain computational problems, such as integer factorization (which underlies RSA encryption), substantially faster than classical computers. The study of quantum computing is a subfield of quantum information science.

'''<font color="#ff8000"> 量子计算Quantum computing</font>'''是利用量子现象，如'''<font color="#ff8000"> 叠加和纠缠Superposition and Entanglement</font>'''来执行计算。执行量子计算的计算机被称为量子计算机。量子计算机被认为能够解决某些计算问题，比如 RSA 加密的基础整数分解，比传统计算机快得多。'''<font color="#ff8000"> 量子计算</font>'''的研究是'''<font color="#ff8000"> 量子信息科学Quantum information science</font>'''的一个分支。

'''<font color="#ff8000"> 量子计算Quantum computing</font>'''是利用量子现象(如'''<font color="#ff8000"> 叠加和纠缠Superposition and Entanglement</font>''')来执行计算。执行量子计算的计算机被称为量子计算机。<ref name=2018Report>{{cite book | title=Quantum Computing : Progress and Prospects (2018) | page= I-5 | publisher=National Academies Press | editor-last1 = Grumbling | editor-first1 = Emily | editor-last2 = Horowitz | editor-first2 = Mark | author= The National Academies of Sciences, Engineering, and Medicine|location=Washington, DC | year=2019 | doi=10.17226/25196|isbn=978-0-309-47969-1 | oclc=1081001288 }}</ref>量子计算机能够从根本上比传统计算机更快地解决比如整数分解(RSA 加密的基础)这类特定的计算问题。'''<font color="#ff8000"> 量子计算</font>'''是'''<font color="#ff8000"> 量子信息科学Quantum information science</font>'''的一个分支。

< ! -- 历史 -- >  

< ! -- 历史 -- >  

Quantum computing began in the early 1980s, when physicist [[Paul Benioff]] proposed a [[quantum mechanics|quantum mechanical]] model of the [[Turing machine]].<ref name="The computer as a physical system">{{cite journal|last1=Benioff|first1=Paul|year=1980|title=The computer as a physical system: A microscopic quantum mechanical Hamiltonian model of computers as represented by Turing machines|journal=Journal of Statistical Physics|volume=22|issue=5|pages=563–591|bibcode=1980JSP....22..563B|doi=10.1007/bf01011339|s2cid=122949592}}</ref>&nbsp;[[Richard Feynman]]&nbsp;and&nbsp;[[Yuri Manin]]&nbsp;later suggested that a quantum computer had the potential to simulate things that a [[computer|classical computer]] could not.<ref>{{cite journal |last1=Feynman |first1=Richard |title=Simulating Physics with Computers |journal=International Journal of Theoretical Physics |date=June 1982 |volume=21 |issue=6/7 |pages=467–488 |doi=10.1007/BF02650179 |url=https://people.eecs.berkeley.edu/~christos/classics/Feynman.pdf |accessdate=28 February 2019 |bibcode=1982IJTP...21..467F |s2cid=124545445 |archive-url=https://web.archive.org/web/20190108115138/https://people.eecs.berkeley.edu/~christos/classics/Feynman.pdf |archive-date=8 January 2019 |url-status=dead }}</ref><ref name="manin1980vychislimoe">{{cite book| author=Manin, Yu. I.| title=Vychislimoe i nevychislimoe| trans-title=Computable and Noncomputable| year=1980| publisher=Sov.Radio| url=http://publ.lib.ru/ARCHIVES/M/MANIN_Yuriy_Ivanovich/Manin_Yu.I._Vychislimoe_i_nevychislimoe.(1980).%5bdjv-fax%5d.zip| pages=13–15| language=Russian| accessdate=2013-03-04| url-status=dead| archiveurl=https://web.archive.org/web/20130510173823/http://publ.lib.ru/ARCHIVES/M/MANIN_Yuriy_Ivanovich/Manin_Yu.I._Vychislimoe_i_nevychislimoe.(1980).%5Bdjv%5D.zip| archivedate=2013-05-10}}</ref> In 1994, [[Peter Shor]] developed a quantum [[algorithm]] for [[Integer factorization|factoring integers]] that had the potential to decrypt [[RSA (cryptosystem)|RSA]]-encrypted communications.<ref>{{cite document|last1=Mermin|first1=David|date=March 28, 2006|title=Breaking RSA Encryption with a Quantum Computer: Shor's Factoring Algorithm|url=http://people.ccmr.cornell.edu/~mermin/qcomp/chap3.pdf|work=Physics 481-681 Lecture Notes |publisher=Cornell University|archive-url=https://web.archive.org/web/20121115112940/http://people.ccmr.cornell.edu/~mermin/qcomp/chap3.pdf|archive-date=2012-11-15}}</ref> Despite ongoing experimental progress since the late 1990s, most researchers believe that "[[Quantum threshold theorem|fault-tolerant]] quantum computing [is] still a rather distant dream."<ref name="preskill2018">{{cite journal|author=John Preskill|date=2018|title=Quantum Computing in the NISQ era and beyond|journal=Quantum|volume=2|pages=79|arxiv=1801.00862|doi=10.22331/q-2018-08-06-79|s2cid=44098998}}</ref> In recent years, investment into quantum computing research has increased in both the public and private sector.<ref>{{cite journal |last1=Gibney |first1=Elizabeth |title=Quantum gold rush: the private funding pouring into quantum start-ups |journal=Nature |date=2 October 2019 |volume=574 |issue=7776 |pages=22–24 |doi=10.1038/d41586-019-02935-4 |pmid=31578480 |bibcode=2019Natur.574...22G |doi-access=free }}</ref><ref>{{Cite news|last=Rodrigo|first=Chris Mills|url=https://thehill.com/policy/technology/482402-trump-budget-proposal-boosts-funding-for-artificial-intelligence-quantum|title=Trump budget proposal boosts funding for artificial intelligence, quantum computing|date=12 February 2020|work=The Hill|access-date=|url-status=live}}</ref> On 23 October 2019, [[Google AI]], in partnership with the U.S. National Aeronautics and Space Administration ([[NASA]]), claimed to have performed a quantum computation that is [[quantum supremacy|infeasible on any classical computer]].<ref>{{Cite web|url=https://www.ibm.com/blogs/research/2019/10/on-quantum-supremacy/|title=On "Quantum Supremacy"|date=2019-10-22|website=IBM Research Blog|language=en-US|access-date=2020-01-21}}</ref>

Quantum computing began in the early 1980s, when physicist [[Paul Benioff]] proposed a [[quantum mechanics|quantum mechanical]] model of the [[Turing machine]].&nbsp;[[Richard Feynman]]&nbsp;and&nbsp;[[Yuri Manin]]&nbsp;later suggested that a quantum computer had the potential to simulate things that a [[computer|classical computer]] could not.  In 1994, [[Peter Shor]] developed a quantum [[algorithm]] for [[Integer factorization|factoring integers]] that had the potential to decrypt [[RSA (cryptosystem)|RSA]]-encrypted communications. Despite ongoing experimental progress since the late 1990s, most researchers believe that "[[Quantum threshold theorem|fault-tolerant]] quantum computing [is] still a rather distant dream." In recent years, investment into quantum computing research has increased in both the public and private sector. On 23 October 2019, [[Google AI]], in partnership with the U.S. National Aeronautics and Space Administration ([[NASA]]), claimed to have performed a quantum computation that is [[quantum supremacy|infeasible on any classical computer]].

Quantum computing began in the early 1980s, when physicist Paul Benioff proposed a quantum mechanical model of the Turing machine.&nbsp;Richard Feynman&nbsp;and&nbsp;Yuri Manin&nbsp;later suggested that a quantum computer had the potential to simulate things that a classical computer could not.  In 1994, Peter Shor developed a quantum algorithm for factoring integers that had the potential to decrypt RSA-encrypted communications. Despite ongoing experimental progress since the late 1990s, most researchers believe that "fault-tolerant quantum computing [is] still a rather distant dream." In recent years, investment into quantum computing research has increased in both the public and private sector. On 23 October 2019, Google AI, in partnership with the U.S. National Aeronautics and Space Administration (NASA), claimed to have performed a quantum computation that is infeasible on any classical computer.

Quantum computing began in the early 1980s, when physicist Paul Benioff proposed a quantum mechanical model of the Turing machine.&nbsp;Richard Feynman&nbsp;and&nbsp;Yuri Manin&nbsp;later suggested that a quantum computer had the potential to simulate things that a classical computer could not.  In 1994, Peter Shor developed a quantum algorithm for factoring integers that had the potential to decrypt RSA-encrypted communications. Despite ongoing experimental progress since the late 1990s, most researchers believe that "fault-tolerant quantum computing [is] still a rather distant dream." In recent years, investment into quantum computing research has increased in both the public and private sector. On 23 October 2019, Google AI, in partnership with the U.S. National Aeronautics and Space Administration (NASA), claimed to have performed a quantum computation that is infeasible on any classical computer.

'''<font color="#ff8000"> 量子计算</font>'''始于20世纪80年代早期，当时物理学家'''<font color="#ff8000"> 保罗 · 贝尼奥夫Paul Benioff</font>'''提出了'''<font color="#ff8000"> 图灵机Turing machine</font>'''的量子力学模型。'''<font color="#ff8000">理查德 · 费曼Richard Feynman和尤里 · 曼宁Yuri Manin</font>'''后来提出，量子计算机具有模拟传统计算机所不具备的潜力。1994年，Peter Shor 开发了一种量子算法，用于分解整数，这种算法有可能解密 rsa 加密的通信。尽管自20世纪90年代后期以来，实验取得了进展，但大多数研究人员认为，“容错量子计算机仍然是一个相当遥远的梦想。”近年来，量子计算研究的投资在公共和私营部门都有所增加。2019年10月23日，谷歌人工智能与'''<font color="#ff8000"> 美国宇航局U.S. National Aeronautics and Space Administration (NASA)</font>'''合作，声称已经完成了在任何传统计算机上都不可能完成的'''<font color="#ff8000"> 量子计算</font>'''。

'''<font color="#ff8000"> 量子计算</font>'''始于20世纪80年代早期，当时物理学家'''<font color="#ff8000"> 保罗 · 贝尼奥夫Paul Benioff</font>'''提出了'''<font color="#ff8000"> 图灵机Turing machine</font>'''的量子力学模型。'''<ref name="The computer as a physical system">{{cite journal|last1=Benioff|first1=Paul|year=1980|title=The computer as a physical system: A microscopic quantum mechanical Hamiltonian model of computers as represented by Turing machines|journal=Journal of Statistical Physics|volume=22|issue=5|pages=563–591|bibcode=1980JSP....22..563B|doi=10.1007/bf01011339|s2cid=122949592}}</ref><font color="#ff8000">理查德 · 费曼Richard Feynman和尤里 · 曼宁Yuri Manin</font>'''后来提出，量子计算机有潜力去模拟传统计算机所无法模拟的东西。<ref>{{cite journal |last1=Feynman |first1=Richard |title=Simulating Physics with Computers |journal=International Journal of Theoretical Physics |date=June 1982 |volume=21 |issue=6/7 |pages=467–488 |doi=10.1007/BF02650179 |url=https://people.eecs.berkeley.edu/~christos/classics/Feynman.pdf |accessdate=28 February 2019 |bibcode=1982IJTP...21..467F |s2cid=124545445 |archive-url=https://web.archive.org/web/20190108115138/https://people.eecs.berkeley.edu/~christos/classics/Feynman.pdf |archive-date=8 January 2019 |url-status=dead }}</ref><ref name="manin1980vychislimoe">{{cite book| author=Manin, Yu. I.| title=Vychislimoe i nevychislimoe| trans-title=Computable and Noncomputable| year=1980| publisher=Sov.Radio| url=http://publ.lib.ru/ARCHIVES/M/MANIN_Yuriy_Ivanovich/Manin_Yu.I._Vychislimoe_i_nevychislimoe.(1980).%5bdjv-fax%5d.zip| pages=13–15| language=Russian| accessdate=2013-03-04| url-status=dead| archiveurl=https://web.archive.org/web/20130510173823/http://publ.lib.ru/ARCHIVES/M/MANIN_Yuriy_Ivanovich/Manin_Yu.I._Vychislimoe_i_nevychislimoe.(1980).%5Bdjv%5D.zip| archivedate=2013-05-10}}</ref>1994年，Peter Shor 开发了一种量子算法，用于分解整数，这种算法有可能解密 rsa 加密的通信。<ref>{{cite document|last1=Mermin|first1=David|date=March 28, 2006|title=Breaking RSA Encryption with a Quantum Computer: Shor's Factoring Algorithm|url=http://people.ccmr.cornell.edu/~mermin/qcomp/chap3.pdf|work=Physics 481-681 Lecture Notes |publisher=Cornell University|archive-url=https://web.archive.org/web/20121115112940/http://people.ccmr.cornell.edu/~mermin/qcomp/chap3.pdf|archive-date=2012-11-15}}</ref>尽管自20世纪90年代后期以来，实验取得了进展，但大多数研究人员认为，“容错量子计算机仍然是一个相当遥远的梦想。”<ref name="preskill2018">{{cite journal|author=John Preskill|date=2018|title=Quantum Computing in the NISQ era and beyond|journal=Quantum|volume=2|pages=79|arxiv=1801.00862|doi=10.22331/q-2018-08-06-79|s2cid=44098998}}</ref>近年来，量子计算研究的投资在公共和私营部门都有所增加。<ref>{{cite journal |last1=Gibney |first1=Elizabeth |title=Quantum gold rush: the private funding pouring into quantum start-ups |journal=Nature |date=2 October 2019 |volume=574 |issue=7776 |pages=22–24 |doi=10.1038/d41586-019-02935-4 |pmid=31578480 |bibcode=2019Natur.574...22G |doi-access=free }}</ref><ref>{{Cite news|last=Rodrigo|first=Chris Mills|url=https://thehill.com/policy/technology/482402-trump-budget-proposal-boosts-funding-for-artificial-intelligence-quantum|title=Trump budget proposal boosts funding for artificial intelligence, quantum computing|date=12 February 2020|work=The Hill|access-date=|url-status=live}}</ref>2019年10月23日，谷歌AI与'''<font color="#ff8000"> 美国宇航局U.S. National Aeronautics and Space Administration (NASA)</font>'''合作，声称已经完成了在任何传统计算机上都不可能完成的'''<font color="#ff8000"> 量子计算</font>'''。<ref>{{Cite web|url=https://www.ibm.com/blogs/research/2019/10/on-quantum-supremacy/|title=On "Quantum Supremacy"|date=2019-10-22|website=IBM Research Blog|language=en-US|access-date=2020-01-21}}</ref>

There are several models of quantum computing, including the quantum circuit model, quantum Turing machine, adiabatic quantum computer, one-way quantum computer, and various quantum cellular automata. The most widely used model is the quantum circuit. Quantum circuits are based on the quantum bit, or "qubit", which is somewhat analogous to the bit in classical computation. Qubits can be in a 1 or 0 quantum state, or they can be in a superposition of the 1 and 0 states. However, when qubits are measured the result of the measurement is always either a 0 or a 1; the probabilities of these two outcomes depend on the quantum state that the qubits were in immediately prior to the measurement. Computation is performed by manipulating qubits with quantum logic gates, which are somewhat analogous to classical logic gates.

There are several models of quantum computing, including the quantum circuit model, quantum Turing machine, adiabatic quantum computer, one-way quantum computer, and various quantum cellular automata. The most widely used model is the quantum circuit. Quantum circuits are based on the quantum bit, or "qubit", which is somewhat analogous to the bit in classical computation. Qubits can be in a 1 or 0 quantum state, or they can be in a superposition of the 1 and 0 states. However, when qubits are measured the result of the measurement is always either a 0 or a 1; the probabilities of these two outcomes depend on the quantum state that the qubits were in immediately prior to the measurement. Computation is performed by manipulating qubits with quantum logic gates, which are somewhat analogous to classical logic gates.

'''<font color="#ff8000"> 量子计算</font>'''有几种模型，包括'''<font color="#ff8000">量子电路模型、量子图灵机、绝热量子计算机、单向量子计算机和各种量子细胞自动机</font>'''。使用最广泛的模型是'''<font color="#ff8000"> 量子电路Quantum circuits </font>'''。量子电路是基于量子比特或'''<font color="#ff8000"> “量子比特”"qubit"</font>'''的，它在某种程度上类似于经典计算中的'''<font color="#ff8000"> “比特”"bit"</font>'''。'''<font color="#ff8000"> 量子比特</font>'''可以处于1或0的量子态，也可以处于1和0的叠加态。然而，当量子比特被测量时，测量结果总是0或1; 这两个结果的概率取决于量子比特在测量之前所处的量子状态。计算是通过'''<font color="#ff8000"> 量子逻辑门Quantum logic gates</font>'''操纵量子比特来完成的，这在某种程度上类似于经典逻辑门。

'''<font color="#ff8000"> 量子计算</font>'''有几种模型，包括'''<font color="#ff8000">量子电路模型、量子图灵机、绝热量子计算机、单向量子计算机和各种量子细胞自动机</font>'''。使用最广泛的模型是'''<font color="#ff8000"> 量子电路Quantum circuits </font>'''。量子电路是基于量子比特或'''<font color="#ff8000"> “量子位”"qubit"</font>'''的，它在某种程度上类似于经典计算中的'''<font color="#ff8000"> “比特”"bit"</font>'''。'''<font color="#ff8000"> 量子比特</font>'''可以处于1或0的量子态，也可以处于1和0的叠加态。然而，当量子比特被测量时，测量结果总是0或1; 这两种结果发生的概率取决于量子比特在被测量之前所处的量子状态。计算是通过'''<font color="#ff8000"> 靠量子逻辑门Quantum logic gates</font>'''操纵量子比特来完成的，这在某种程度上类似于经典逻辑门。

< ! -- 物理实现 -- >  

< ! -- 物理实现 -- >  

There are currently two main approaches to physically implementing a quantum computer: analog and digital. Analog approaches are further divided into [[quantum simulator|quantum simulation]], [[quantum annealing]], and [[adiabatic quantum computation]]. Digital quantum computers use [[quantum logic gate]]s to do computation. Both approaches use qubits.<ref name=2018Report/>{{rp|2–13}} There are currently a number of significant obstacles in the way of constructing useful quantum computers. In particular, it is difficult to maintain the quantum states of qubits as they are prone to [[quantum decoherence]], and quantum computers require significant [[error correction]] as they are far more prone to errors than classical computers.<ref>{{cite book |doi=10.1007/1-4020-8068-9_8 |chapter=Challenges in Reliable Quantum Computing |title=Nano, Quantum and Molecular Computing |year=2004 |last1=Franklin |first1=Diana |last2=Chong |first2=Frederic T. |pages=247–266 |isbn=1-4020-8067-0 }}</ref><ref>{{cite news |last1=Pakkin |first1=Scott |last2=Coles |first2=Patrick |title=The Problem with Quantum Computers |url=https://blogs.scientificamerican.com/observations/the-problem-with-quantum-computers/ |publisher=Scientific American |date=10 June 2019}}</ref>

There are currently two main approaches to physically implementing a quantum computer: analog and digital. Analog approaches are further divided into [[quantum simulator|quantum simulation]], [[quantum annealing]], and [[adiabatic quantum computation]]. Digital quantum computers use [[quantum logic gate]]s to do computation. Both approaches use qubits.

There are currently two main approaches to physically implementing a quantum computer: analog and digital. Analog approaches are further divided into quantum simulation, quantum annealing, and adiabatic quantum computation. Digital quantum computers use quantum logic gates to do computation. Both approaches use qubits.

There are currently two main approaches to physically implementing a quantum computer: analog and digital. Analog approaches are further divided into quantum simulation, quantum annealing, and adiabatic quantum computation. Digital quantum computers use quantum logic gates to do computation. Both approaches use qubits.

目前实现量子计算机主要有两种方法: 模拟和数字。模拟方法进一步分为'''<font color="#ff8000">量子模拟、量子退火模拟和绝热量子计算</font>'''。数字量子计算机使用'''<font color="#ff8000"> 量子逻辑门</font>'''进行计算。两种方法都使用量子比特。

目前实现量子计算机主要有两种方法: 模拟和数字。模拟方法进一步分为'''<font color="#ff8000">量子模拟、量子退火模拟和绝热量子计算</font>'''。数字量子计算机使用'''<font color="#ff8000"> 量子逻辑门</font>'''进行计算。两种方法都使用量子比特。<ref name=2018Report/>{{rp|2–13}} There are currently a number of significant obstacles in the way of constructing useful quantum computers. In particular, it is difficult to maintain the quantum states of qubits as they are prone to [[quantum decoherence]], and quantum computers require significant [[error correction]] as they are far more prone to errors than classical computers.<ref>{{cite book |doi=10.1007/1-4020-8068-9_8 |chapter=Challenges in Reliable Quantum Computing |title=Nano, Quantum and Molecular Computing |year=2004 |last1=Franklin |first1=Diana |last2=Chong |first2=Frederic T. |pages=247–266 |isbn=1-4020-8067-0 }}</ref><ref>{{cite news |last1=Pakkin |first1=Scott |last2=Coles |first2=Patrick |title=The Problem with Quantum Computers |url=https://blogs.scientificamerican.com/observations/the-problem-with-quantum-computers/ |publisher=Scientific American |date=10 June 2019}}</ref>

The prevailing model of quantum computation describes the computation in terms of a network of [[quantum logic gate]]s.<ref name="Nielson-Chuang">{{Cite book|title=Quantum Computation and Quantum Information: 10th Anniversary Edition|last1=Nielsen|first1=Michael A.|last2=Chuang|first2=Isaac L.|date=2010|publisher=Cambridge University Press|isbn=9780511976667|location=Cambridge|doi=10.1017/cbo9780511976667|url=http://cds.cern.ch/record/465953}}</ref>

The prevailing model of quantum computation describes the computation in terms of a network of [[quantum logic gate]]s.

The prevailing model of quantum computation describes the computation in terms of a network of quantum logic gates.

The prevailing model of quantum computation describes the computation in terms of a network of quantum logic gates.

A memory consisting of <math display="inline">n</math> bits of information has <math display="inline">2^n</math> possible states. A vector representing all memory states thus has <math display="inline">2^n</math> entries (one for each state). This vector is viewed as a probability vector and represents the fact that the memory is to be found in a particular state.

A memory consisting of <math display="inline">n</math> bits of information has <math display="inline">2^n</math> possible states. A vector representing all memory states thus has <math display="inline">2^n</math> entries (one for each state). This vector is viewed as a probability vector and represents the fact that the memory is to be found in a particular state.

一个由<math display="inline">n</math> 比特信息组成的内存有 <math display="inline">2^n</math> 可能的状态。因此，一个代表所有内存状态的向量具有 <math display="inline">2^n</math> 条目(每个状态一个)。这个向量被看作是一个概率向量，它代表了一个事实，即内存将在一个特定的状态下被找到。

一个由<math display="inline">n</math> 比特信息组成的内存有 <math display="inline">2^n</math> 种可能的状态。因此，一个代表所有内存状态的向量具有 <math display="inline">2^n</math> 个条目(每个状态一个)。这个向量被看作是一个概率向量，它代表了一个事实——内存将在一个特定的状态下被找到。