Quantum Computing with Atoms. Christopher Monroe

(1)

Christopher Monroe

Quantum Computing

with Atoms

(2)

Computing and Information

Alan Turing (1912-1954)

universal computing machines

Claude Shannon (1916-2001)

quantify information: the bit

𝐻 = − ෍

𝑖=1

𝑘

𝑝

_𝑖

𝑙𝑜𝑔

₂

𝑝

_𝑖

moving CPU memory tape read/write device 011

0 1 1 0 0

1

(3)

ENIAC (1946)

МЭСМ (1949)

Colossus (1943)

vacuum

tubes

solid-state

transistor

(1947)

(4)

Moore’s Law

exponential growth in computing

Transistor density relative to 1978

1980 1990 2000 2010 2018 100,000 10,000 1,000 100 10 1

There's Plenty of Room at the Bottom

(1959)

“

When we get to the very, very small world

–

say circuits of

seven atoms

–

we have a lot of new things that would happen

that represent

completely new opportunities for design

. Atoms

on a small scale behave like nothing on a large scale, for they

satisfy the

laws of quantum mechanics…”

Richard

Feynman

(5)

Quantum bits

entanglement: “wiring

without wires

”

superposition

a

|0



+

b|1

|0



state

|1



state

Quantum Information Science

|0



state

Prob = |

a

|

2

|1

state

Prob = |

b

|

2

measurement:

“state collapse”

Entanglement

superposition

a

|0



|0



+

b|1|1

|0



|0



state

|1|1

state

OR

(6)

Good News…

parallel processing

on

2

N

_inputs

a

₀

|000



+

a

₁

|001



+

a

₂

|010



+

a

₃

|011



a

₄

|100



+

a

₅

|101



+

a

₆

|110



+

a

₇

|111



f(x)

N=300 qubits have more

configurations than there are

particles in the universe!

e.g., N=3

qubits

…Bad News…

measurement gives

random result

f(x)

depends

on

all

inputs

…Good News!

quantum interference

David Deutsch

(early 1990s)

(7)

A quantum computer can factor numbers

exponentially faster

than classical computers

39 = 3



13 (…easy)

38647884621009387621432325631 =

?



?

P. Shor (1994)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

quantum

wavefunction

𝜓(𝑛)

(8)

Application: Optimization

Traveling Salesman problem

what is the

shortest path

through N

cities?

Molecular Simulations

• designer materials

• new catalysts

• protein folding

(9)

A quantum computer differs more from a laptop…

(10)

Quantum Computer Technologies

adapted from

Science, Dec 2016

IonQ, Honeywell Intel, HRL, SQC Microsoft

Neutral atoms

Neutral atoms, like ions, store qubits within electronic states. Interactions through excitation to Rydberg states 1 97% 20

Many qubits, 2D and maybe 3D

Lasers needed, spaghetti physics, atoms escape

Technologies QuEra ColdQuanta

Photonics

Photonic qubits interact via linear elements

Linear optical gates, integrated on-chip No memory, not clear how to scale

Xanadu

Google, Quantum Diamond Atom Computing PsiQuantum

(11)

(12)

2 _S

1/2

|



=

|0,0



|



=

|1,0



Atomic (hyperfine) qubit (

171 Yb

+

)

n

_HF

/2

p

=

12.642 812 118 GHz

(13)

2 _S

1/2

2 _P

1/2

369 nm

2.1 GHz

g/2p

= 20 MHz

|



|



# photons collected in 50 ms Probabilit y 0 10 20 30 40 50 60

|



171 _Yb

+

_{Qubit Detection}

n

_HF

/2

p

=

12.642 812 118 GHz

(14)

2 _S

1/2

2 _P

1/2

369 nm

g/2p

= 20 MHz

|



|



2.1 GHz # photons collected in 50 ms Probabilit y 0 10 20 30 40 50 60

|



171 _Yb

+

_{Qubit Detection}

High-NA collection + SNSPD (J. Kim, Duke)

- 6.5% of fluorescence detected

-

99.93% qubit detection in 12

m

s

(15)

171 _Yb

+

_{Qubit Manipulation}

D

= 33 THz

355 nm

2 _P

3/2

g/2p

= 20 MHz

n

_HF

=

12.642 812 118 GHz

|



(100 MHz, 10psec)

D. Hayes et al., PRL 104, 140501 (2010)

66 THz

2 _P

1/2

2 _S

1/2

|



𝑔

₁

𝑔

₂

(16)

(17)

Monroe Group

Atomic Physics Lab

Photo: Phil Schewe

(18)

ENIAC (1946)

МЭСМ (1949)

Colossus (1943)

(19)

(20)

(21)

Quantum Computer Optical Controller

Laser

………..

32-channel

AOM

power stabilizer rep rate stabilizer beam-pointing stabilizer beam-pointing stabilizer

DOE

rf inputs (200MHz)

AOM

S. Debnath,...

Nature

536 , 63 (2016)

N. Linke,...

PNAS

114 , 13 (2017)

Full “Quantum Stack” architecture

(22)

Quantum Computer Optical Controller

Laser

………..

32-channel

AOM

power stabilizer rep rate stabilizer beam-pointing stabilizer beam-pointing stabilizer

DOE

rf inputs (200MHz)

AOM

S. Debnath,...

Nature

536 , 63 (2016)

N. Linke,...

PNAS

114 , 13 (2017)

(23)

Year Application

Reference

Collaborator

Institute

2013 Frustration and AFM order Science 340, 583 J. Freericks Georgetown 2014 Lieb-Robinson propagation Nature 511, 198 A. Gorshkov NIST

2015 Spin-1 Dynamics Phys. Rev. X 5, 021026 A. Retzker Hebrew University 2016 Manybody Localization Nat. Physics 12, 907 D. Huse, P. Hauke Princeton, Innsbruck 2017 Hidden Shift, Toffoli-3 Gate PNAS 114, 13 M. Roetteler Microsoft, Inc.

Grover Nat. Comm. 8, 1918 D. Maslov NSF Toffoli-4 Gate Thesis, Debnath D. Maslov NSF Prethermalization Science Adv. 3, e1700672 Z. Gong, A. Gorshkov NIST Time Crystaline Order Nature 543, 217 N. Yao Berkeley Dynamical Phase Transition Nature 551, 601 A. Gorshkov NIST [[4,2,2]] Error Detection Science Adv. 3, e1701074 K. Brown Duke 2018 Fredkin Gate, Fermi-Hubbard PRA 98, 052334 S. Johri Intel Corp.

Bayesian Game QST 3, 045002 N. Solmeyer ARL Qubit Detection ML J. Phys. B 51 174006 M. Hafezi JQI 2019 Full Adder, Parallel CNOTs Nature 567, 61 D. Maslov NSF

Generative Modeling ML Science Adv. 5, eaaw9918 A. Perdomo-Ortiz NASA

Deuteron VQE Simulation PRA 100, 62319 R. Pooser, O. Shehab ORNL, IonQ Validating stabilizer states Phys. Rev. A 99, 042337 Amir Kalev QuICS UMD

Quantum Scrambling Nature 567, 61 B. Yoshida, N. Yao Perimeter, Berkeley Circuit QAOA arXiv:1906.02699 T. Hsieh, S. Johri Perimeter, Intel Corp. Benchmarks and Comparison arXiv: 1905.11349 M. Martonosi Princeton

Analog QAOA arXiv:1906.02700 A. Gorshkov, S. Jordan NIST, Microsoft Inc. Quasiparticle Confinement arXiv: 1912.11117 A. Gorshkov NIST

Efficient QAOA (Max-Cut, Deuteron) arXiv:1906.00476 Isaac Kim, Omar Shehab Stanford, IonQ Dynamical mean field theory arxiv: 1910.04735 Ross Duncan, Ivan Rungger Cambridge QC, NPL

(24)

Year Application

Reference

Collaborator

Institute

2020 Many-body dephasing arXiv: 2001.02477 F. Marquardt MPL Erlangen Quantum walks theory arXiv:2001.11197 B. Radhakrishnan, C. Chandrashekar ARL, Chennai Quantum walks, cellular automaton arXiv:2002.02537 B. Radhakrishnan, C. Chandrashekar ARL, Chennai [[9,1,3]] Bacon/Shor code arXiv:2009.11482 K. Brown Duke

NMR Deconvolution in progress E. Demler Harvard

Measurement-induced phase xsition in progress M. Gullens, D. Huse, N. Yao NIST, Princeton, Berkeley Classical Verification of QC in progress U. Vazarani, N. Yao, T. Vidick Berkeley, CalTech

Cross platform benchmarking in progress Peter Zoller Innsbruck Lattice Gauge Thy in progress Z. Davoudi UMD Ising Scattering in progress Yannick Meurice U. Iowa Circuit-based MBL in progress Sonika Johri Intel Corp. Schwinger model simulation in progress Zohreh Davoudi UMD

Envariance measures in progress Wojciech Zurek Los Alamos Para-particle simulations in progress C. M. Alderete, Blas R. Lara UMD, INAOE Edge-cover problem QAOA in progress B. Sundar, K. Hazzard Innsbruck, Rice Lee-Yang Zeroes in progress Lex Kemper NCSU

Triangle game in progress Akimasa Miyake UNM Molecular Cluster simulations in progress Nicolas Sawaya Intel Corp. Ring-molecule dynamics Q-Sim in progress Rob Parrish QCWare Chaos-QAOA in progress Gregory Quiroz, O. Shehab APL, IonQ GAN-compression of circuits in progress Xiaodi Wu QuICS UMD QFT- based benchmarking in progress Yannick Meurice U. Iowa Block-diagonalization via Grover in progress Sonika Johri Intel Corp. term-ordered VQE in progress M. Martonosi Princeton Cluster state generation in progress Robert Raussendorf, Vito Scarola UBC, VaTech Block-optimized VQE in progress Peter Zoller Innsbruck

Norbert Linke

(UMD/JQI)

Marko Cetina

(UMD/JQI)

new faculty @Duke

Crystal Noel

(UMD/JQI)

new faculty @Duke

(25)

(1) Prepare spins along

𝑥

(2) Quench spins to

(3) Measure along

𝑥

increase

𝑩/𝑱

𝐻 = ෍

𝑖<𝑗

𝑱

|𝑖 − 𝑗|

𝛼

𝜎

𝑥𝑖

𝜎

𝑥 𝑗

+ 𝑩 ෍

𝑖

𝜎

_𝑧𝑖

order

along

𝑥

align

along

𝑧

A. Gorshkov (JQI/NIST)

D. Huse (Princeton)

S. Johri (Intel)

N=53

qubits

𝐵/𝐽

20

18

16

14

12 0 0.5 1.0 1.5 2.0

avg

. l

arges

t domain

size

Exotic Magnetism

(26)

Cosmology + Quantum Gravity

Quantum Scrambling

Scrambling

: “complete diffusion” of quantum information, relevant to information evolution in black holes

N. Yao (UC Berkeley)

B. Yoshida (Perimeter)

L. Susskind (Stanford)

EPR

ۧ

|0

ۧ

|𝜓

ۧ

|0

ۧ

|0

ۧ

|0

ۧ

|0

ۧ

|0

ۧ

|𝜓

𝑈

†

Bell

†

input

qubit

Successful teleportation if U

scrambles

output

qubit

Landsman, et al., Nature 567, 61 (2019)

In 1935, Einstein and Rosen showed that

widely-separated black holes can be connected by a tunnel

through space-time, now known as a

wormhole

Physicists suspect that the connection in a wormhole

and the connection in quantum entanglement

are the same thing, just on a vastly different scale!

entanglement

(27)

Nature 417, 709 (2002)

Science Advances 3, e1601540 (2017)

Shuttling between

multiple zones

Linear shuttling through

single zone

>100 qubits

Quantum Computer Scaling I

NIST-Boulder

Univ. Mainz

(28)

Technology:

Integrated photonics and

switches, SNSPD detector array

Plan:

Multicore quantum

processing

optical switch detector array QMem QComm

(29)

Single trapped 138_Ba+_atom beam-splitter optical fiber

photo-detector photo-_detector

ns pulses @ 100 kHz

p ~ 4%

Making single photons

S

_1/2

P

_1/2

D

_3/2

649.7nm

m_J=+3/2 m_J=-1/2 m_J=+1/2

138 _Ba

+

493.4nm

t

=10ns

m_J=+1/2

t

(

m

s)

t

(

m

s)

𝑔

2

(𝜏)

𝑔

2

(𝜏)

coincidence count rate

𝑔

2

(0)

Higginbottom, et al. (Innsbruck), New J. Phys. 18, 093038 (2016)

(30)

Single trapped 174_Yb+_atom beam-splitter optical fiber

2ps pulses @ 5.3 MHz

l

=369nm

g (2 ) (t)

excellent single photon source

Making single photons

p

~ 3%

delay (ns)

𝑔

2

(0)

Higginbottom, et al. (Innsbruck), New J. Phys. 18, 093038 (2016)

C. Crocker, et al., Optics Express 27, 28143 (2019)

-1000 -500 0 500 1000

P. Maunz, et al., Nature Physics 3, 538 (2007)

(31)

Single trapped 174_Yb+_atom beam-splitter optical fibers

delay (ns)

Hong, Ou, Mandel, PRL 59, 2044 (1987) Y.H. Shih & C. O. Alley, PRL 61, 2921 (1988)

Santori, et al., Nature, 419, 594 (2002) Kaltenbaek, et al, PRL, 96, 240502 (2006) Legero, et al., PRL, 93, 070503 (2004). Thompson, et al., Science, 313, 74 (2006). Felinto, et al. Nature Physics, 2, 844 (2006). Beugnon, et al. Nature, 440, 779 (2006). P. Maunz, et al., Nature Physics 3, 538 (2007)

g(2)_(t) 2ps pulses @ 8.1 MHz Single trapped 174_Yb+_atom

T

_integ

~ minutes

p

2

_~

₁₀

-3

1 meter

2-photon interference

spinless atom

(no qubit)

(32)

Heralded coincident events:

(H

₁

& V

₂

) or (V

₁

& H

₂

)

→ |

↓↑

 -

|

↓↑



(H

₁

& V

₁

) or (V

₂

& H

₂

)

→ |

↓↑

 +

|

↓↑



(H

₁

& H

₁

) or (H

₂

& H

₂

)

→ |

↓↓



(V

₁

& V

₁

) or (V

₂

& V

₂

)

→ |

↑↑



Photonic Linkage between Atomic Qubits

𝑅

_𝑒𝑛𝑡

=

1

2 𝑅𝑝

2

D. Hucul, et al., Nature Phys. 11, 37 (2015)

C. Balance, et al, Phys. Rev. Lett. 124, 110501

Current State-of-art:

𝑝 = 𝜂

_𝐷

𝑇

𝑑Ω

4𝜋

= .35 .6 .1 = 2%

𝑅 = 1 𝑀𝐻𝑧

𝑹

_𝒆𝒏𝒕

≈ 𝟏𝟖𝟎 𝒔𝒆𝒄

−𝟏

Hong, Ou, Mandel, PRL 59, 2044 (1987) Y.H. Shih & C. O. Alley, PRL 61, 2921 (1988) Simon & Irvine, PRL 91, 110405 (2003) L.-M. Duan, et. al., QIC 4, 165 (2004) Y. L. Lim, et al., PRL 95, 030505 (2005)

2007: Trapped Ions[Nature 449, 68–71] 2013: Trapped Neutrals[PRL 110, 140403] 2014: NV-diamond[Science 345, 532] 2015: Quantum Dots[Nature Phys. 12, 218] 2016: Superconductors[PRX 6, 031036] Single trapped 171_Yb+_atom beam-splitter optical fibers

2ps pulses @ 8.1 MHz Single trapped 171_Yb+ _atom

p

2

_~

₁₀

-3

1 meter

(33)

Duan and Monroe, Rev. Mod. Phys. 82, 1209 (2010) Li and Benjamin, New J. Phys. 14, 093008 (2012) Monroe, et al., Phys. Rev. A 89, 022317 (2014)

Vision I: Modular Scaling with Photonic Interconnects

0.001 Hz before

~

200 Hz now

(34)

Chip

scale

Lab

scale

Rackmount

scale

2016

2018

0.5m

2020

0.1m

2021

0.01m

2023

10m

2025

Bench

scale

2m

(35)

IonQ was founded in 2015 by

Chris Monroe and Jungsang Kim,

headquartered in College Park, MD

We have built several generations of full-stack quantum

computer systems, with cloud access via commercial servers.

IonQ is a leader in quantum computing, with

technology based on

individual atomic qubits

,

having high quality and reconfigurable quantum

operations. We have a clear scaling roadmap to tackle

problems that are impossible with classical computers.

(36)

www.ionq.com

College Park, MD

70 employees

Google Ventures New Enterprise Associates

Venture Investors

($84M raised)

(37)

Quantum computer

(38)

(39)

N=24 qubits preprogrammed

Loading

zone

Quantum

Computing

zone

autoloading register

(40)

Lower Errors through Encoding

ۧ

𝛼

|0 +

𝛽

|1

ۧ

𝑝 ⟹ 𝐶𝑝

2 Quantum Error Correction

error prob.

𝑝

error prob.

𝑝

(per qubit)

𝛼

ۧ

|00000 +

|10010 +

ۧ

|01001 +

ۧ

|10100

ۧ

+

|01010 −

ۧ

|11011 −

ۧ

|00110 −

ۧ

|11000

ۧ

−

|11101 −

ۧ

|00011 −

ۧ

|11110 −

ۧ

|01111

ۧ

−

|10001 −

ۧ

|01100 −

ۧ

|10111 +

ۧ

|00101

ۧ

|11111 +

|01101 +

ۧ

|10110 +

ۧ

|01011

ۧ

+

|10101 −

ۧ

|00100 −

ۧ

|11001 −

ۧ

|00111

ۧ

−

|00010 −

ۧ

|11100 −

ۧ

|00001 −

ۧ

|10000

ۧ

−

|01110 −

ۧ

|10011 −

ۧ

|10111 +

ۧ

|11010

ۧ

+

𝛽

⟹

C. Shannon (classical)

P. Shor

R. Calderbank

A. Steane

(41)

University

Industry

No problem with quantum physics

Take research “where it goes”

Don’t “build” things here

✓



Not so familiar with quantum physics

May not build things for science

Engineering, manufacturing, reliability

✓



✓

National

Laboratory

No problem with quantum physics

Research for science and applications

Engineering, manufacturing, reliability

Little history in the field (for now)

✓



(42)

(43)

The NPI Team behind the NQI

H.R. 6227

David Lang OSA Ed White NPI Jennifer O’Bryan SPIE Laura Kolton OSA

(44)

• Build quantum computers from the

highest performance components

• Use quantum computers for science

• Co-design

next generation quantum

computers based on scientific use cases

• Translate

quantum technology to national

and commercial societal needs

A Quantum Computer

User Facility that will

Marko

Cetina

Crystal

Noel

Ken

Brown

Robert

Calderbank

Jungsang

Kim

Chris

Monroe

• Physics

• Electrical &

Computer

Engineering

• Chemistry

• Mathematics

• Computer

Science