Single photon sources using a coherently driven Rydberg atom gas - - PowerPoint PPT Presentation

Single photon sources using a coherently driven Rydberg atom gas

David Petrosyan

Using single emitter strongly coupled to a resonant cavity (Γ<g)

g s e

photon Cavity Excitation pulse

How to produce single photons?

How to produce single photons?

Using the DLCZ scheme (probabilistically)

g s e g s e

Write pulse photon Idler Read pulse Signal photon

Using massive Rydberg superatom (full blockade)

g e r

pulse Excitation pulse Control photon

How to produce single photons?

Nearly-deterministic, free-space source

• f single photons
• Prepare a single atom in an excited state (using a laser)
• Transfer the single excitation to a large atomic ensemble to

create a spin-wave with proper spatial phase (using long-range

dipole-dipole interactions between the atomic Rydberg states)

Combine the best properties of the CQED, Rydberg SA & DLCZ schemes

• Convert the spin wave to photon wave-packet emitted in

the phase-matched direction (using a control laser)

• D. Petrosyan, K. Mølmer, arXiv:1806.07094 [quant-ph]

Step 1: Single atomic excitation

g

z

i u s d e

|Ψ1⟩ = |u⟩ ⊗ |G⟩ |G⟩ ≡ |g1, g2, . . . , gN⟩

Step 2: Single collective excitation

s u i

z

g e d

r

D δ ∆ D

( )

s

−

r S ~D r ( )

Ω

|Ψ2⟩ = |d⟩ ⊗ |S⟩ |S⟩ ≡ 1

¯ D

N

j=1 ˜

Djeik0·rj |g1, g2, . . . , sj, . . . , gN⟩ ˜ Dj ≡ −D(r−rs)Ω

∆

¯ D ≡ N

j | ˜

Dj|21/2 D(r − rs) =

C3 |r−rs|3(1 − 3 cos2 ϑ)

C3 = ℘si℘du

4π0 ,

℘ ≈ n2ea0

Step 3: Single photon emission

s u i

z

g e d ˆ E

( ) r

Ω

( )

s

−

r S ~D r

c

ˆ E

|Ψ3⟩ = |d⟩ ⊗ |S⟩ ⊗ |1phot⟩ |1phot⟩ ≡

k ak |1k⟩

ak = −˜ gk(t)

j ˜ Dj ¯ D ei(k0−kc−k)·rj

˜ gk ≃

gkΩ∗ c Γe(ck−ωeg)/2+i|Ωc|2 for t Γe/2 |Ωc|2

θx

θ

y

z y x θ =π/2

x y

θ =0 θ =0

x y

c

θ =π/2

x y

∆θ ∆θ

k k k k k

−

P∆Ω ≃ ηN∆Ω/4π 0.7

∆Ω = 2π(1 − cos ∆θ)

Phased-array optical antenna with atoms in a lattice

• A. Grankin, P. O. Guimond, D. V. Vasilyev, B. Vermersch, P. Zoller, arXiv:1802.05592 [quant-ph]

Shaping the spatial distribution of the emitted radiation by tailoring the phase and amplitudes of the antenna atoms

Rydberg implementation Fixed atomic positions, Control of spatial phase and amplitude of Ωd Subwavelength interatomic distances, two or more layers

Single photon filter using dipolar exchange induced transparency with Rydberg atoms

• D. Petrosyan, NJP 19, 033001 (2017)

Electromagnetically Induced Transparency

e

Γ

g ˆ E ˆ E

−4 −2 2 4

Detuning ∆/γe

−0.6 −0.4 −0.2 0.0 0.2 0.4 0.6

Dispersion

0.0 0.2 0.4 0.6 0.8 1.0

Absorption

e

∆

η

Stationary propagation 2LA medium susceptibility

Electromagnetically Induced Transparency

g

d d

Ω

η Γ

r

−4 −2 2 4

Detuning ∆/γe

−0.6 −0.4 −0.2 0.0 0.2 0.4 0.6

Dispersion

0.0 0.2 0.4 0.6 0.8 1.0

Absorption

r ˆ E ˆ E

e

δ ∆

Γ

e Ω

Stationary propagation EIT (3LA) susceptibility

Pulse propagation in EIT medium

N ρ r e g V=

ˆ E ˆ E

g

( ) z,t Ωd v ∆

e

Ωd

r

Γ Γ η

Dipolar Exchange Induced Transparency

d u

s

∆r

ρ i r e g N

x

n = J L= /2 Γ

e

∆ ( ) D z

ˆ E

as

D D

ˆ E

D Ω

s c g

v z ( ) ( ) z,t

c

∆

as

η

DEIT medium response

2 4 6 8 10 12 14 16 18 20 22 24 -10

• 8
• 6
• 4
• 2

2 4 6 8 10 0.2 0.4 0.6 0.8 1

e

Absorption Position z ( m) Probe detuning

µ

∆/γ

Summary

Strong, long-range dipole-dipole exchange interactions between Rydberg atoms can be used to couple a singe atom to a large atomic ensemble Single photons can then be emitted with large probability into the phase-matched spatial direction [arXiv:1806.07094] State transfer between single atomic qubits coupled to optical phase-array antennas can be achieved [arXiv:1802.05592] Excitation of a single emitter can be converted to a collective medium excitation In DEIT ns “spin” atoms can play the role of the quantized control field Ωd of the EIT The system can serve as photon number filter or transistor for np ≤ ns photons

Poster: Simulating spin-lattice models with cold Rydberg atoms