atoms

hep.caltech.edu

atoms

Building Exotic Quantum Systems

-Toward Scalable Quantum Networks

Quantum optics with cold

atoms trapped in 1d- and 2dphotonic

crystals

Entangled

Entangled

Chen-Lung Hung (postdoc)

Prof. Kimble Quantum Optics

group

Caltech physics information day

March 28, 2013

ORCHID

NSSEFF

QuMPASS


Quantum Networks

➪ Fundamental Scientific Question and Diverse Technical Challenges

Quantum Nodeprocess

/ store

quantum information

Quantum Channel -

transport / distribute

quantum entanglement

Theoretical issues

• Does it “work” – capabilities beyond any classical system

• Characterization of entangled states ➪ Computationally intractable?

Experimental implementation

• Physical processes for reliable generation, processing, & transport

of quantum states


Quantum Networks for Quantum Simulation

“spin”

“interaction”

“spin”

L. Amico, R. Fazio, A. Osterloh, & V. Vedral,

“Entanglement in many-body systems,” Rev. Mod. Phys. 80, 517 (2008)

R. P. Feynman, “Simulating Physics with Computers,”

Intl. J. of Th. Physics 21, 467 (1982)


Building Exotic Quantum Systems -

➪ “Lego blocks” for the realization of complex quantum systems

➪ Fundamental scientific question and diverse technical challenges

Laboratory realization of physical systems

different in kind than have heretofore existed

• Quantum information processing

• Quantum measurement

• Quantum simulation

Characterization and verification

of entanglement for multipartite systems


1) A Quantum Interface

between Matter and Light

What’s inside here?

Atoms

• Strongly coupled atom – photon

via cavity QED

Photons

χ (κ ,γ )

• Cirac, Zoller, Kimble & Mabuchi, PRL 78, 3221 (1997)


2) A Quantum Interface

between Matter and Light

What’s inside here?

• Ensemble of ~ 10 5 atoms

• Strong interaction of single photons and collective spin excitations

• Raymer; Bigelow, Kuzmich, Mandel; …., Fleischhauer, Lukin, …

• Duan, Cirac, Lukin & Zoller – DLCZ, Nature 414, 413 (2001)

Writing and Reading

single spin excitations

via Raman processes

Write

Field 2

Field 1

Read


Quadripartite entanglement

• 4 atomic ensembles sharing 1 quantum of spin excitation

K. Choi, A. Goban, S. Papp, S. J. van Enk & H. J. Kimble, Nature 468, 412 (2010)

W ideal

= 1 2

⎡( 1000 + e iφ 1

0100 ) + e iφ 0010 + e iφ 2


0001

( )



exp

⇔ ˆρ atoms

exp

Inferred fidelity F atoms

exp

F atoms

for atomic W state at memory time τ 0

= 0.2µs:

exp

= W ideal

ˆρ atoms

W ideal

= 0.9 ± 0.1

Fluorescent image

from 4 ensembles


3) A Quantum Interface

between Matter and Light

What’s inside here?

• Strong focusing of one photon onto a localized atom

• Efficient collection of atomic emission of single photons

“Single atom in free space as a quantum aperture,”

van Enk & Kimble, PRL 61, 051802 (2000)


Strong interactions of single photons & atoms

A new frontier to achieve 1), 2), 3) in one setting

What’s inside here?

1. Multi-pass interactions and small mode volume in an optical cavity (cQED)

2. Large optical depth (e.g., atomic ensembles)

3. Strong focusing (localization) of light


Demonstration of a State-Insensitive Nanofiber Trap

A. Goban et al., Phys. Rev. Lett. 109, 033603 (2012); arXiv:1203.5108v1

Nano-fiber

SiO 2 nano-fiber

diameter = 430nm

E in in


E reflected

Current experiment - r 1

0.07

Projected - r 1

0.9

E transmitted


Cavity QED with Atomic Mirrors

D. Chang, L. Jiang, A. Gorshkov & H.J. Kimble, N. J. Phys. 14 063003 (2012); arXiv:1201.0643

In

Cavity QED

Out

Quantum protocols

-Single photon generation

-Entanglement distribution

-Quantum logic

- atoms

- photons

- …

Mirror atoms

Impurity

atom

Mirror atoms

1d waveguide

Mirrors as coherent quantum memories

strongly coupled to single impurity atom


Building Blocks for Scalable Quantum Information Processing*

d I


p


q

d M

*D. Chang, L. Jiang, A. Gorshkov & H.J. Kimble,

New J. Phys. 14 063003 (2012); arXiv:1201.0643


Photon-Mediated Dipole-Dipole Interactions*

π



è Infinite range spin-spin interactions with sinusoidal coupling set by Γ 1D


• Quantum many-body physics

• Quantum information processing: universal gate set with built-in “wiring”

=exited state

=ground state

*D.E. Chang, L. Jiang, A.V. Gorshkov, and H.J. Kimble, N. J. Phys. 14 063003 (2012)


Self Organization of Atoms along a 1-D Waveguide

D. Chang, I. Cirac, & H.J. Kimble, Phys. Rev. Lett. 110, 113606 (2012)


A Exciting Way Forward -

Quantum Optics and Atomic Physics

with 1-D and 2-D Photonic Bandgap Structures

Kimble – Painter at Caltech

D. Chang at ICFO

I. Cirac at MPQ

K. Choi at KIST

Oskar Painter

Caltech

~400 nm


Quantum Optics with 1-d Photonic Structures

Ø Large atom-photon interaction: single atom reflectivity r 1

> 0.9

Ø Strong coupling in cQED

Single-photon Rabi frequency 2g 0

>10 GHz

Ø Wave-vector “engineering”

ω(k) 2.0

ω 2

1.5

Long-range atom-atom interactions

mediated by single photons

Quantum many-body physics for

internal & external degrees of freedom

ω 1

k 1

= k 2

1.0

0.5

0.0

0.0 0.5 1.0 1.5

k


Single color optical trap (blue trap) and strong coupling

C.-L. Hung & S. Meenehan, arXiv:1301.5252 (2013)

x

x

y

z

y

z

x


Device Design and Fabrication – Oskar Painter, Caltech

1-d photonic waveguide butt coupled to conventional optical fiber

Efficient butt-coupled fiber

• Efficient “on chip” quantum connectivity

provided by photons over integrated optical networks.

100 μm

Evanescent atom-light coupling

2 μm

Photonic crystal mirrors/cavities

1 mm

2 μm


A new experiment platform – Kimble 1 & Painter 2 Groups

N i ~ 10 7 Cs atoms

at ρ ~ 10 12 /cm 3

T ~ 10µK

Optical fiber

butt-coupled

to SiN device

SiN device –

~ 300nm x 200nm

waveguide

terminated by

1-d mirror

2 μm

1.5mm

N f ~ 10 6 Cs atoms

at ρ ~ 10 11 /cm 3

T < 10µK

Evanescent

atom-light coupling

1. Aki Goban

Chen-Lung Hung

Jonathan Hood

Su-Peng Yu

2. Sean Meenehan

Justin Cohen

Richard Norte


Toward scalable quantum networks enabled by Quantum Optics

Fiber optic

technology

Atom-nanofiber systems

Fiber-coupled atomic ensemble

Atoms

Single trapped atom

near microtoroid

K. Vahala (Caltech-ENS)

Atoms

Atoms

Photonic crystal cavity

O. Painter (Caltech-ENS)

Linear circuits

+

Quantum functionality


1 mm

H. Jeff Kimble Group

East Bridge - Basement

Photonic crystal trap

A. Goban

J. Hood

S. P. Yu

C.-L. Hung (postdoc)

Self-organization near 1dwaveguide

D. Ding

J. Muniz

J. H. Lee (postdoc)

Cavity QED in photonic

crystal structure

D. J. Alton

A. McClung

P. Forn-Diaz (postdoc)

M. Pototschnig (postdoc)

O. Painter Group

S. Meenehan

Justin Cohen

R. Norte

Theory collaborator

D. Chang (ICFO)

I. Cirac (MPQ)

S. van Enk (Oregon)

A. V. Gorshkov (IQI)

L. Jiang (IQI)

K. S. Choi (KIST)


IQIM

2mm

Caltech Institute for Quantum Information and Matter

A Physics Frontiers Center

with support from the Gordon and Betty Moore Foundation

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NSSEFF

!""

Caltech Institute for Quantum Information and Matter

NSF Physics Frontiers Center

with support from the Gordon and Betty Moore Foundation

QuMPASS

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