量子计算外文翻译中英文.docx

量子计算外文翻译中英文.docx

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量子计算外文翻译中英文

量子计算中英文2019

英文

FROMBITSTOQUBITS,FROMCOMPUTINGTOQUANTUMCOMPUTING:

ANEVOLUTIONONTHEVERGEOFAREVOLUTIONINTHECOMPUTINGLANDSCAPE

PirjanAlexandru;PetroşanuDana-Mihaela.

ABSTRACT

The"Quantum Computing"concepthasevolvedtoanewparadigminthe computing landscape,havingthepotentialtostronglyinfluencethefieldofcomputerscienceandallthefieldsthatmakeuseofinformationtechnology.Inthispaper,wefocusfirstonanalysingthespecialpropertiesofthe quantum realm,asaproperhardwareimplementationofa quantum computing systemmusttakeintoaccounttheseproperties.Afterwards,wehaveanalyzedthemainhardwarecomponentsrequiredbya quantum computer,itshardwarestructure,themostpopulartechnologiesforimplementing quantum computers,likethetrappediontechnology,theonebasedonsuperconductingcircuits,aswellasotheremergingtechnologies.Ourstudyoffersimportantdetailsthatshouldbetakenintoaccountinordertocomplementsuccessfullytheclassicalcomputerworldofbitswiththeenticingoneofqubits.

KEYWORDS:

 Quantum Computing,Qubits,TrappedIonTechnology,Superconducting Quantum Circuits,Superposition,Entanglement,Wave-ParticleDuality, Quantum Tunnelling

1.INTRODUCTION

The"Quantum Computing"concepthasitsrootsinthe"Quantum Mechanics"physicssubdomainthatspecifiesthewayhowincrediblysmallparticles,uptothesubatomiclevel,behave.Startingfromthisconcept,the Quantum Computing hasevolvedtoanewparadigminthe computing landscape.Initially,theconceptwasputforwardinthe1980sasameanforenhancingthe computing capabilityrequiredtomodelthewayinwhich quantum physicalsystemsact.Afterwards,inthenextdecade,theconcepthasdrawnanincreasedlevelofinterestduetotheShor'salgorithm,which,ifithadbeenputintopracticeusinga quantum computing machine,itwouldhaveriskeddecryptingclassifieddataduetotheexponentialcomputationalspeeduppotentialofferedby quantumcomputing [1].

However,asthedevelopmentofthe quantum computing machineswasinfeasibleatthetime,thewholeconceptwasonlyoftheoreticalvalue.Nowadays,whatwasoncethoughttobesolelyatheoreticalconcept,evolvedtobecomearealityinwhich quantum informationbits（entitled"qubits"）canbestoredandmanipulated.Bothgovernmentalandprivatecompaniesalikehaveanincreasedinterestinleveragingtheadvantagesofferedbythehugecomputationalspeeduppotentialprovidedbythe quantum computing techniquesincontrasttotraditionalones[2].

Oneoftheaspectsthatmakethedevelopmentof quantum computersattractiveconsistsinthefactthattheshrinkageofsilicontransistorsatthenanometerscalethathasbeentakingplaceformorethan50yearsaccordingtoMoore'slawbeginstodrawtoahalt,thereforearisingtheneedforanalternatesolution[3].

Nevertheless,themostimportantfactorthataccountsforboostingtheinterestin quantum computing isrepresentedbythehugecomputationalpowerofferedbythesesystemsandthefactthattheirdevelopmentfrombothhardwareandsoftwareperspectiveshasbecomeareality. Quantum computing managedtosurpassthecomputabilitythesisofChurchTuring,whichstatesthatforany computing device,itspowercomputationcouldincreaseonlyinapolynomialmannerwhencomparedtoa"standard"computer,entitledtheTuringmachine[4].

Duringthetime,hardwarecompanieshavedesignedandlaunched"classical" computing machineswhoseprocessingperformancehasbeenimprovingoverthetimeusingtwomainapproaches:

firstly,theoperationshavebeenacceleratedthroughanincreasedprocessingclockfrequencyandsecondly,throughanincreaseinthenumberofoperationsperformedduringeachprocessingclock'scycle[5].

Althoughthe computing processingpowerhasincreasedsubstantiallyafterhavingappliedtheabove-mentionedapproaches,theoverallgainhasremainedinaccordancewiththethesisofChurch-Turing.Afterwards,in1993,BernsteinandVaziranihavepublishedin[6]atheoreticalanalysisstatingthattheextendedChurch-Turingthesiscanbesurpassedbymeansof quantum computing.Inthefollowingyear,PeterShorhasprovedinhispaperthatbymeansof quantumcomputing thefactorizationofalargenumbercanbeachievedwithanexponentially computing speedupwhencomparedtoaclassical computing machine[7-9].Astonishingasthetheoreticalframeworkwas,aviablehardwareimplementationwasstilllackingatthetime.

Thefirststepsforsolvingthisissuehavebeenmadein1995,whenscientistshavelaidthefoundationsforatechnologybasedonatrappedionsystem[10]andafterwards,in1999,foratechnologyemployingsuperconductingcircuits[11].Basedontheadvancementoftechnology,overthelastdecades,researchershaveobtainedhugeprogressinthisfield,thereforebecomingabletobuildandemploythefirst quantum computing systems.

Whileinthecaseofaclassical computing machinethedataisstoredandprocessedasbits（havingthevalues0or1）,inthecaseofa quantum computingmachine,thebasicunitof quantum informationunderwhichthedataisstoredandprocessedisrepresentedbythe quantum bits,orqubitsthatcanhavebesidesthevaluesof0and1,acombinationofboththesevaluesinthesametime,representinga"superposition"ofthem[12].

Atacertainmomentintime,thebinaryvaluesofthenbitscorrespondingtoaclassicalcomputerdefineacertainstateforit,whileinthecaseofa quantumcomputer,atacertainmomentintime,anumberofnqubitshavethepossibilitytodefinealltheclassicalcomputer'sstates,thereforecoveringanexponentialincreasedcomputationalvolume.Nevertheless,inordertoachievethis,thequbitsmustbe quantum entangled,anon-localpropertythatmakesitpossibleforseveralqubitstobecorrelatedatahigherlevelthanitwaspreviouslypossibleinclassical computing.Inthispurpose,inordertobeabletoentangletwoorseveralqubits,aspecificcontrolledenvironmentandspecialconditionsmustbemet[13].

Duringthelastthreedecades,alotofstudieshavebeenaimingtoadvancethestateofknowledgeinordertoattainthespecialconditionsrequiredtobuildfunctional quantum computing systems.Nowadays,besidesthemostpopulartechnologiesemployedinthedevelopmentof quantum computing systems,namelytheonesbasedontrappedionsystemsandsuperconductingcircuits,awiderangeofotheralternativeapproachesarebeingextensivelytestedincomplexresearchprojectsinordertosuccessfullyimplementqubitsandachieve quantum computing [14].

Onemusttakeintoaccountthefactthatalongwiththenewhardwarearchitecturesandimplementationsof quantum computing systems,newchallengesarisefromthefactthatthisnew computing landscapenecessitatesnewoperations, computing algorithms,specializedsoftware,allofthesebeingdifferentthantheonesusedinthecaseofclassicalcomputers.

Aproperhardwareimplementationofa quantum computing systemmusttakeintoaccountthespecialpropertiesofthe quantum realm.Therefore,thispaperfocusesfirstonanalyzingthesecharacteristicsandafterwardsonpresentingthemainhardwarecomponentsrequiredbya quantum computer,itshardwarestructure,themostpopulartechnologiesforimplementing quantum computers,likethetrappediontechnology,theonebasedonsuperconductingcircuits,aswellasotheremergingtechnologies.Ourdevelopedresearchoffersimportantdetailsthatshouldbetakenintoaccountinordertocomplementsuccessfullytheclassicalcomputerworldofbitswiththeenticingoneofqubits.

2.SPECIALPROPERTIESOFTHE QUANTUM REALM

Thehugeprocessingpowerof quantum computersresultsfromthecapacityof quantum bitstotakeallthebinaryvaluessimultaneouslybutharnessingthisvastamountofcomputationalpotentialisachallengingtaskduetothespecialpropertiesofthe quantum realm.Whilesomeofthesespecialpropertiesbringconsiderablebenefitstowards quantum computing,thereareothersthatcanhinderthewholeprocess.

Oneofthemostaccurateandextensivelytestedtheorythatcomprehensiblydescribesourphysicalworldis quantum mechanics.Whilethistheoryoffersintuitiveexplanationsforlarge-scaleobjects,whilestillveryaccuratealsoatthesubatomiclevel,theexplanationsmightseemcounterintuitiveatthefirstsight.Atthe quantum level,anobjectdoesnothaveacertainpredefinedstate,theobjectcanbehavelikeaparticlewhenameasurementisperformeduponitandlikeawaveifleftunmeasured,thisrepresentingaspecial quantum propertyentitledwave-particleduality[15].

Theglobalstateofa quantum systemisdeterminedbytheinterferenceofthemultitudeofstatesthattheobjectscansimultaneouslyhaveata quantum level,thestatebeingmathematicallydescribedthroughawavefunction.Actually,thesystem'sstateisoftendescribedbythesumofthedifferentpossiblestatesofitscomponents,multipliedbyacoefficientconsistinginacomplexnumber,representing,foreachstate,itsrelativeweight[16,17].Forsuchacomplexcoefficient,bytakingintoconsiderationitstrigonometric（polar）form,onecanwriteitundertheformAew=A（cos6+isind）,whereA>0representsthemoduleofthiscomplexnumberandisdenotedasthe"amplitude",whileвrepresentstheargumentofthecomplexnumber,beingdenotedas"thephaseshift".Therefore,thecomplexcoefficientisknownifthetworealnumbersAandвareknown.

Alltheconstitutivecomponentsofa quantum systemhavewave-likeproperties,thereforebeingconsidered"coherent".Inthecaseofcoherence,thedifferentstatesofthe quantum componentsinteractbetweenthem,eitherinaconstructivemannerorin