PBG CAVITY IN NV-DIAMOND FOR QUANTUM COMPUTING - PowerPoint PPT Presentation

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PBG CAVITY IN NV-DIAMOND FOR QUANTUM COMPUTING. Team: John-Kwong Lee (Grad Student) Dr. Renu Tripathi (Post-Doc) Dr. Gaur Pati (Post-Doc). Supported By: DARPA, AFOSR. OPERATIONS NEEDED FOR A QUANTUM COMPUTER. STATE PREPARATION: e.g. OPTICAL PUMPING. SINGLE BIT OPERATION: e.g. -PULSE.

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PBG CAVITY IN NV-DIAMOND FOR QUANTUM COMPUTING

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PBG CAVITY IN NV-DIAMOND

FOR QUANTUM COMPUTING

Team:

John-Kwong Lee (Grad Student)

Dr. Renu Tripathi (Post-Doc)

Dr. Gaur Pati (Post-Doc)

Supported By:

DARPA, AFOSR


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OPERATIONS NEEDED FOR A QUANTUM COMPUTER

STATE PREPARATION: e.g. OPTICAL PUMPING

SINGLE BIT OPERATION: e.g. -PULSE

TWO-BIT OPERATIONS: e.g. CNOT

METHOD: LASER CONTROLLED SPIN EXCITATION

(DARK RESONANCE)

MEDIUM: SHB CRYSTAL, e.g. NV-DIAMOND


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QUANTUM COMPUTING IN NV-DIAMOND: BASIC IDEA

KEY FEATURES:

BOTTOM LINES:

SOLID STATE

SCALABLE TO >1000

PARALLEL POSSIBLE

(1 cm)3

(5 mm)3

SPIN AS QUBIT

OPTICAL OPERATION & READOUT

OPTICAL INTERCONNECT POSSIBLE

>5000 OPS BEFORE DECOHERENCE

NATURALLY SUITED TO TYPE 2 QC


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ADIABATIC TRANSFER VIA THE DARK STATE

|-> = (2|a> - 1|b>)/

|+> = (1|a> + 2|b>)/

|e

|e

|+> - |e>

|a> - |e>

|b> - |e>

|->=|b>

|->=|a>

|-

|+

|b

|a

|a> + |e>

|b> + |e>

|+> + |e>

1

EQUIVALENT TO A -PULSE

AMPLITUDE

TOPOLGICALLY ROBUST

0

TIME


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METHOD 1: CAVITY ENHANCED COUPLING

STEP 1: COHERENCE TRANSFER VIA CAVITY QED

ATOM

A

ATOM

B

g

1

2

1

2

g

g

0

0

1

1

A

B

A

B


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STEP 2: ENTANGLEMENT (CNOT) VIA CAVITY QED

COHERENCE TRANSFER VIA RAMAN

INITIAL CONDITIONS:

ATOM A -- ELECTRON COHERENCE

ATOM B -- NUCLEAR COHERENCE

AFTER ADIABATIC TRANSFER:

ATOM A -- PURE STATE

ATOM B -- PRODUCT STATE

“CNOT” WITH RAMAN p PULSE

ATOM A

ATOM B

ATOM A

ATOM B

1

2

1

2

PURE

STATE

PRODUCT

STATE

1

2

RAMAN

C-“NOT”

e

n

e

n

1 2

1

0

1

2

0

0

1 2

0

g

g

g

g

1 2

1

2

2

0

0

1 2


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ADIABATIC COHERENCE TRANSFER VIA CAVITY-QED DARK STATE

ADIABATIC COHERENCE TRANSFER

CAVITY VACUUM COUPLING g

ATOM

1

ATOM

2

1

2

g

INTENSITY

1

0

1

2

TIME

RAMAN DARK STATES

INITIAL

ONE CAVITY PHOTON

ATOM 1

ATOM 2

|e1>

|e1 b2 0>

|b1 e2 0>

|e2>

NO CAVITY

PHOTONS

1

2

2

1

g

g

g

g

a

b

|b1>

|a1>

|a2>

|b2>

|a1 b2 0>

|b1 b2 1>

|b1 a2 0>

|b1 b2 0>

a

b

0

1

2 g

12

1 g


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DARK STATE QUANTUM COMPUTING IN NV-DIAMOND: NECESSARY ENERGY LEVELS

g

h

g

h

c

d

a

b

c

d

e

f

a2

b2

a

b

e

f

a1

b1

QUBIT 1

QUBIT 2


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DARK STATE QUANTUM COMPUTING IN NV-DIAMOND: ROLE OF STORAGE LEVELS

c

d

a

b

e

f

a

b

c

d

c

d

b

a

b

a

b

c

d

e

f

e

f

a

a

b

e

f


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EXPLICIT CONSTRUCT FOR ENTANGLEMENT

a

c

b

b

c

a

c

a

a

a

c

b

b

a

c

b

c

b

a

a

a


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2mI

Df

Df

IZ

DARK STATE QUANTUM COMPUTING IN SHB CRYSTAL: CANDIDATE MATERIALS

IZ

5

g

h

1

-1

g

h

4.6 MHz

1D2

P

3

1

-1

4.8MHz

3E

1

Q

0

0

Pr:YSO

NV-DIAMOND

1

e

f

c

d

-1

1

10.2 MHz

3H4

3

c

d

4.6 MHz

3A1

17.3 MHz

1

-1

a

b

2.8 MHz

a

b

e

5

f

0

0

-

Sgn(mI)

SZ

+

1

-1

[A]

[B]


Issues with n v diamond l.jpg

ISSUES WITH N-V DIAMOND

SPIN-ORBIT COUPLING SOMEWHAT INHIBITED

  • RAMAN TRANSITIONS PARTIALLY FORBIDDEN

  • WORK NEAR ANTI-CROSSING, LEVELS MIX

    PERMANENT HOLE BURNING

  • NO CW SIGNAL, CITE RE-ARRANGEMENT

  • RE-PUMP ON PHONON SIDEBAND

DYE

LASER

ARGON

LASER

REPUMP

638 nm

ZERO

PHONON

LINE

PHONON

SIDEBAND

S= ±1

ABSORPTION

2.88

GHz

120 MHz

S= 0

514

638

0

1050 G

B-FIELD

WAVELENGTH (nm)


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EXPERIMENTAL SETUP FOR DARK RESONANCE IN DIAMOND

18

LO

APD

20 MHz

D

AOM

~638nm

R

APERTURE

AOM

R

D

P

DIAMOND

P

C

AOM

C

S = -1

B-FIELD

A

SCREEN

S = 0

120 MHz

DYE

ARGON

SPOTS ON SCREEN

SPOT SIZES: ~ 0.3 mm

BRAGG

SIGNAL

D

R

MATCHED

INTENSITIES:

(BEAT W/ LO)

®

COUPLING -- 14 mW

13 W/cm

2

PROBE -- 14 mW

P

C

A

ARGON

READ -- 16 mW

REPUMP


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DETECTION OF OPTICALLY INDUCED SPIN ALIGNMENT IN NV-DIAMOND

20 MHz

P

C

R

D

S = -1

120 MHz

S = 0

CAN BE INTERPRETED AS SPATIALLY VARYING COLLECTIVE SINGLE SPIN OPERATIONS


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EIT AS EVIDENCE OF EFFICIENT STATE PREPARATION IN NV-DIAMOND

P

LEVEL DIAGRAM

P

C

64

56

48

P

C

40

8.5 MHz

EIT amplitude (%)

120

MHz

S = -1

32

24

S = 0

16

8

0

-20

-10

0

10

20

Probe Beam Detuning (MHz)


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SPIN ALIGNMENT AMPLITUDE VS. MAGNETIC FIELD STRENGTH

LEVEL DIAGRAM

  • NDFWM SIGNALS:

  • CENTRAL FREQUENCY 120 MHZ

  • COUPLING 7 W/cm2 = 1.4 Isat

  • PROBE 1 W/cm2 = 0.3 Isat(SCANNED)

  • READ 4 mW

  • SPOT SIZE 300 mm

20 MHz

AOM TUNING LIMIT

~638nm

R

D

P

C

120

MHz

INTENSITY (ARB.)

S = -1

S = 0

ANTI-CROSSING

B = 1050 G

140

120

100

DIFF. FREQ. (MHz)


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METHOD 2: DIPOLE-DIPOLE INTERACTION

10

CONTROLLED NOT WITH

CONTROL-NOT WITH DIPOLE-DIPOLE INTERACTION

NEAR DIPOLE-DIPOLE INTERACTION

W

p

APPLY OPTICAL 2

PULSE WITH

1

W

CONTROL ATOM IN |b

>, NOTHING HAPPENS --EXCITED STATE SPLIT,

NOT RESONANT

1

2

b

b

b

b

®

CONTROL ATOM IN |c

>, SIGN |c

> IS REVERSED:

| c

c

>

-

| c

c

>

1

2

1

2

2

1

1

2

1

2

p

PHASE SHIFT GATE

EQUIVALENT TO CONTROLLED-NOT IN ROTATED BASIS

ATOM IN |b

>

ATOM IN |c

>

2

2

|a

>

|a

>

1

2

|a

b

>- |b

a

>

g

1

2

1

2

|a

>

|a

b

>+ |b

a

>

1

g

g

W

1

2

1

2

W

1

W

b

1

a

a

1

b

2

2

1

1

|c

>

|b

>

|b

>

2

|c

>

|c

>

1

2

|c

>

1

1

1

ATOM 1

ATOM 2

No

Excites

TARGET

CONTROL

excitation

optical

1

W

transition

l

Ö

g

g

g

= 0.006 (

/r)

(

)

3

A

B

Absorption of

W

Frequency of

1


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Diamond

SiO2

SiO2

Hole filled with

nonlinear-optic

glass

300 nm

20 nm


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Holes filled with

nonlinear-optic

glass

Anomalous hole

also filled with

nonlinear-optic glass

SiO2

SiO2

Cavity


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PMMA (E-Beam Litho)

SiO2 (CF4/CHF3 RIE)

Polyimide (O2 RIE)

Alumina (BCl3 RIE)

SiO2 (CF4/CHF3 RIE)

Diamond (O2 RIE)

SiO2


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SIMULATION OF THE TWO-DIMENSIONAL ISING MODEL,

ISOMORPHIC TO THE PROBLEM OF THE MAXIMUM INDEPENDENT SET


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