Quantum Computers Siva Desaraju Bindu Katragadda Manusri Edupuganti presented by.

Quantum ComputersQuantum Computers

Siva DesarajuSiva Desaraju

Bindu KatragaddaBindu Katragadda

Manusri EdupugantiManusri Edupuganti

presented bypresented by

OutlineOutlineIntroductionIntroductionQuantum computationQuantum computationImplementationImplementationQuantum compilerQuantum compilerError correctionError correctionArchitectureArchitectureClassificationClassificationFabricationFabricationChallengesChallengesAdvantages over classical computersAdvantages over classical computersApplicationsApplicationsRecent advancesRecent advancesTimelineTimelineConclusionConclusion

IntroductionIntroduction

SuperpositionSuperposition Simultaneously possess two or more valuesSimultaneously possess two or more values

EntanglementEntanglement Quantum states of two atoms correlated even though spatially Quantum states of two atoms correlated even though spatially

separated!!!separated!!! Albert Einstein baffled “spooky action at a distance”Albert Einstein baffled “spooky action at a distance”

Quantum MechanicsQuantum Mechanics Why? – Moore’s lawWhy? – Moore’s law Study of matter at atomic level (The power of atoms)Study of matter at atomic level (The power of atoms) Classical physics laws do not applyClassical physics laws do not apply

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Bits n QubitsBits n QubitsClassical computers 0 or 1 (bits)Classical computers 0 or 1 (bits) High/low voltageHigh/low voltage

Quantum computers 0 or 1 or 0 & 1 (Qubits)Quantum computers 0 or 1 or 0 & 1 (Qubits) Nuclear spin up/down 0 or 1Nuclear spin up/down 0 or 1 Isolated atom spin up & down 0 & 1Isolated atom spin up & down 0 & 1

Represent more with less (n bits 2Represent more with less (n bits 2nn states) states)

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” To be or not to be. That is the question”

– William ShakespeareThe classic answers: ”to be” or ”not to be”

The quantum answers: ”to be” or ”not to be” or

a x (to be) + b x (not to be)

Quantum ComputationQuantum Computation

Prime factorization (Cryptography)Prime factorization (Cryptography) Peter Shor’s algorithmPeter Shor’s algorithm Hard classical computation becomes easy quantum Hard classical computation becomes easy quantum

computationcomputation Factor n bit integer in O(nFactor n bit integer in O(n33))

Search an unordered listSearch an unordered list Lov Grover’s algorithmLov Grover’s algorithm Hard classical computation becomes less hard Hard classical computation becomes less hard

quantum computationquantum computation n elements in nn elements in n1/21/2 queries queries

Implementation modelImplementation model

Quantum programQuantum unitary transforms (gates)

Quantum measurements

Classical computation

Classical control flow decisions

Quantum compiler

Instruction stream

Classical bit instruction stream

Early quantum computation - Circuit model(ASIC)Early quantum computation - Circuit model(ASIC)

Quantum CompilerQuantum Compiler

Static precompilerStatic precompiler End-to-end error probabilityEnd-to-end error probability

Dynamic compilerDynamic compiler Accepts the precompiled binary code & Accepts the precompiled binary code &

produces an instruction streamproduces an instruction stream

Error CorrectionError Correction

Localized errors on a few qubits can have global impactLocalized errors on a few qubits can have global impact

Hamming codeHamming code

Difficulty of error correcting quantum statesDifficulty of error correcting quantum states Classical computers – bit flipClassical computers – bit flip Quantum computers – bit flip + phase flipQuantum computers – bit flip + phase flip Difficulty in measurement (collapses superposition)Difficulty in measurement (collapses superposition)

Quantum error correction codeQuantum error correction code [n,k] code uses n qubits to encode k qubits of data[n,k] code uses n qubits to encode k qubits of data Extra bits (n-k) are called ancilla bitsExtra bits (n-k) are called ancilla bits Ancilla bits are in initial stateAncilla bits are in initial state

ArchitectureArchitecture

Aims of efficient architectureAims of efficient architecture Minimize error correction overheadMinimize error correction overhead Support different algorithms & data sizesSupport different algorithms & data sizes Reliable data paths & efficient quantum Reliable data paths & efficient quantum

memorymemory

Major componentsMajor components Quantum ALUQuantum ALU Quantum memoryQuantum memory Dynamic schedulerDynamic scheduler

Architecture contd…Architecture contd…

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Quantum ALUQuantum ALU

Sequence of transformsSequence of transforms the Hadamard (a radix-2, 1-qubit Fourierthe Hadamard (a radix-2, 1-qubit Fourier transform)transform) identity (I, a quantum NOP)identity (I, a quantum NOP) bit flip (X, a quantum NOT)bit flip (X, a quantum NOT) phase flip (Z, which changes the signs of amplitudes)phase flip (Z, which changes the signs of amplitudes) bit and phase flip (Y)bit and phase flip (Y) rotation by π/4 (S)rotation by π/4 (S) rotation by π/8 (T)rotation by π/8 (T) controlled NOT (CNOT)controlled NOT (CNOT)

Quantum MemoryQuantum Memory

Reliable memoryReliable memory

Refresh unitsRefresh units

Multiple memory banksMultiple memory banks

Quantum wiresQuantum wires

TeleportationTeleportation

Quantum swap gatesQuantum swap gates

Cat stateCat state

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Dynamic SchedulerDynamic Scheduler

Dynamic scheduler algorithm takes Dynamic scheduler algorithm takes Input - logical quantum operations, Input - logical quantum operations,

interleaved with classical control flow interleaved with classical control flow constructsconstructs

Output - physical individual qubit operationsOutput - physical individual qubit operations

Uses knowledge of data size & physical qubit Uses knowledge of data size & physical qubit error rateserror rates

ClassificationClassification

Quantum ComputerQuantum Computer

Liquid Quantum Computer Solid Quantum Computer

SiSi2929 Doping Doping Phosphorous DopingPhosphorous Doping

Liquid Quantum ComputersLiquid Quantum Computers

NMR TechnologyNMR Technology

DisadvantagesDisadvantages Massive redundancyMassive redundancy Not scalableNot scalable

Solid Quantum ComputersSolid Quantum Computers

Why siliconWhy silicon

Chip design aimsChip design aims Capturing & manipulating individual sub Capturing & manipulating individual sub

atomic particlesatomic particles Harnessing, controlling & coordinating millions Harnessing, controlling & coordinating millions

of particles at onceof particles at once

SiSi2929 Doping Doping

Need for Silicon 29 (SiNeed for Silicon 29 (Si2929) doping) doping

FabricationFabrication

AdvantagesAdvantages

DisadvantagesDisadvantages

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Phosphorous dopingPhosphorous doping

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FabricationFabrication

STM technology to pluck individual atoms STM technology to pluck individual atoms from hydrogenfrom hydrogen PHPH33 used instead of P used instead of P

ChallengesChallenges

DecoherenceDecoherence

Chip fabricationChip fabrication

Error correctionError correction

Advantages over Classical Advantages over Classical computerscomputers

Encode more informationEncode more information

PowerfulPowerful

Massively parallelMassively parallel

Easily crack secret codesEasily crack secret codes

Fast in searching databasesFast in searching databases

Hard computational problems become Hard computational problems become tractabletractable

ApplicationsApplications

DefenseDefense

CryptographyCryptography

Accurate weather forecastsAccurate weather forecasts

Efficient searchEfficient search

TeleportationTeleportation

……

UnimaginableUnimaginable

TimelineTimeline2003 - A research team in Japan demonstrated the first solid state 2003 - A research team in Japan demonstrated the first solid state device needed to construct a viable quantum computerdevice needed to construct a viable quantum computer

2001 - First working 7-qubit NMR computer demonstrated at IBM’s 2001 - First working 7-qubit NMR computer demonstrated at IBM’s Almaden Research Center. First execution of Shor’s algorithm.Almaden Research Center. First execution of Shor’s algorithm.

2000 - First working 5-qubit NMR computer demonstrated at IBM's 2000 - First working 5-qubit NMR computer demonstrated at IBM's Almaden Research Center. First execution of order finding (part of Almaden Research Center. First execution of order finding (part of Shor's algorithm). Shor's algorithm).

1999 - First working 3-qubit NMR computer demonstrated at IBM's 1999 - First working 3-qubit NMR computer demonstrated at IBM's Almaden Research Center. First execution of Grover's algorithm.Almaden Research Center. First execution of Grover's algorithm.

19981998 - First working 2-qubit NMR computer demonstrated at - First working 2-qubit NMR computer demonstrated at University of California Berkeley.University of California Berkeley.

1997 - MIT published the first papers on quantum computers based 1997 - MIT published the first papers on quantum computers based on spin resonance & thermal ensembles.on spin resonance & thermal ensembles.

1996 - Lov Grover at Bell Labs invented the quantum database 1996 - Lov Grover at Bell Labs invented the quantum database search algorithmsearch algorithm

1995 - Shor proposed the first scheme for quantum error correction1995 - Shor proposed the first scheme for quantum error correction

Conclusion…will this be ever Conclusion…will this be ever true?true?

Millions into researchMillions into research

With a 100 qubit computer you can With a 100 qubit computer you can represent all atoms in the universe.represent all atoms in the universe.

If you succeed, the world will be at your If you succeed, the world will be at your feetfeet

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ReferencesReferences

[1][1]http://www.cs.washington.edu/homes/oskin/Oskin-A-Practical-Archttp://www.cs.washington.edu/homes/oskin/Oskin-A-Practical-Architecture-for-Reliable-Quantum-Computers.pdfhitecture-for-Reliable-Quantum-Computers.pdf

[2][2] http://www.qubit.orghttp://www.qubit.org

[3][3] http://www.nature.comhttp://www.nature.com

[4][4] http://www.wikipedia.comhttp://www.wikipedia.com

[5][5] http://www.howstuffworks.comhttp://www.howstuffworks.com

[6][6] http://www.physicsweb.org/toc/world/11/3http://www.physicsweb.org/toc/world/11/3

[7][7] http://www.cs.ualberta.ca/~bulitko/qc/schedule/slides/QCSS-http://www.cs.ualberta.ca/~bulitko/qc/schedule/slides/QCSS-2002-06-18.ppt2002-06-18.ppt

[8][8] http://physics.about.com/cs/quantumphysics/http://physics.about.com/cs/quantumphysics/

[9][9] http://www.trnmag.com/Stories/2002/082102/Chip_ http://www.trnmag.com/Stories/2002/082102/Chip_ design_aims_for_quantum_leap_082102.htmldesign_aims_for_quantum_leap_082102.html

Puzzled???Puzzled???

"I think I can safely say that nobody understands quantum mechanics."

- Richard P. Feynman

“Anybody who thinks they understand quantum physics is wrong."

- Niels Bohr