Ilja Gerhardt

Coherent State Preparation

of a Single MoleculeIlja Gerhardt, Gert Wrigge,

Jaesuk Hwang, Gert Zumofen, Alois Renn& Vahid Sandoghdar Centre fo r

Qu ant umTechn o log ies , Sing a p o reSw iss Federa l Institute o f Technology Zurich

Ilja Gerhardt

Single molecule spectroscopy

• Dibenzantanthrene, DBATT

• Embedded in organic matrices

• e.g. Shpol’skii

|2

|1

Ilja Gerhardt

Fluorescence Excitation

Wide-field illuminationT=1.4 Kl ~ 615 nm, 30 GHz scan

Ilja Gerhardt

Lifetime Limited Linewidth…

• Lifetime limited linewidth• T1~10ns

Ilja Gerhardt

Efficient Excitation

Sam pleSIL

Solid Immersion Lens

0 0 .5-0 .5

-0 .5

0 .5

1-1-1

1

X [ ]μ m

0

Y []

μm

FWHM=370nm

Wrigge et al., Nature Physics 4, 60 - 66 (2008)

Ilja Gerhardt

Single Molecule Extinction

2468

101214

10Co

unts

per S

econ

d3

0

L a s e r D e t u n i n g [ M H z ] Laser D etu n in g [M H z]

88

9 2

9 6

10 0

Tran

smiss

ion [

%]

115

12 0

12 5

13 0 10Counts per Second

3

FW H M = 17.1 M H z

Fluorescence Extinction

• Fluorescence detection • Extinction up to 11.5%• Mollow Triplet

Wrigge et al., Nature Physics 4, 60 - 66 (2008)

Ilja Gerhardt

Photon statistics

Ilja Gerhardt

Photon statistics

• Super Poissonian• Rabi-oscillations

T. Basché et al., Phys. Rev. Lett., 69, 1516 (1992)

Ilja Gerhardt

• Rabi-oscillations– Short pulse?– Single photons?– Transmission

Change?– Phase gate?

Autocorrelation

• Driving the molecule to a defined point of excitation• It stays there for t=T1

Ilja Gerhardt

Short Pulse Experiments

• Driving the Bloch-vector to a defined point of excitation detecting the red-shifted fluorescence (µ r22)

gSt

g00

|eñ

|gñ

Ilja Gerhardt

The Experiment

Rb: Gibbs; Molecules: Orlowski

Ilja Gerhardt

Idea & Realization

Phys. Rev. A 79, 011402(R) (2009)

Ilja Gerhardt

Ilja Gerhardt

AOM• 2.9 nsec possible (limit: AOM, focussing)

• 1 MHz Rep. rate (limit: Pulsegenerator DG535)

• Problem: Peak vs. BG (limit: RF-Switching, scattering)

Phys. Rev. A 79, 011402(R) (2009)

[n s]

- 6 0 d B

- 30 d B

0 d B

- 50 0 50

Ilja Gerhardt

Setup

#

Phys. Rev. A 79, 011402(R) (2009)

Ilja Gerhardt

Time Evolution

10 201550 25

Excitat ionPu lse

StokesFlo rescen ce220 n W110 0 n W

6 050403020100

Tim e D elay [ns]

Even

ts [a

.u.]

Phys. Rev. A 79, 011402(R) (2009)

Ilja Gerhardt

Integrated Mode• Also integrated experiments

possible:–Illuminate with short pulses–Record Integrated red-shifted

fluorescence

Phys. Rev. A 79, 011402(R) (2009)

0 500 1000 1500 200002468

10

Intensity

Integ

rated

Fluo

resce

nce

Ilja Gerhardt

E-Field

Ired

The Signal

• Background• Decay within pulse

Phys. Rev. A 79, 011402(R) (2009)

Time [ns]

Inte

nsit

y [a

.u.]

Ilja Gerhardt

Setup

Phys. Rev. A 79, 011402(R) (2009)

Ilja Gerhardt

0 0 .13 0 .97 2.38 4 .56 7.28 10Averaged In ten sity [n W ]

Pu lse A rea [ ]πSt

okes

Fluo

resce

nce [

10 cp

s]3

0

5

10

15

1 3 5 7 9 11

Integrated Photons

π

2π

3π

4π

5π

6π

7π

8π

9π

10π

??500 photonsper pulse

Ilja Gerhardt

Setup

Phys. Rev. A 79, 011402(R) (2009)

Ilja Gerhardt

Detuning DependenceInt

ensit

y

Laser Detuning-1000 -500 0 500 10000

200

400

600

800

1000

Inten

sity

L aser D etuning-10 0 0 -50 0 0 50 0 10 0 00

20 0

40 0

6 0 0

80 0

10 0 0

Inten

sity

Laser Detuning-400 -200 0 200 4000

200

400

600

800

1000

Inten

sity

Laser Detuning-400 -200 0 200 4000

200

400

600

800

1000

Phys. Rev. A 79, 011402(R) (2009)

Ilja Gerhardt

Frequency Dependence

500 500250Laser Detuning [MHz]

Inte

nsity

[a.u

.]

0 2500

0.020.10.20.40.81.21.6

22.4

Ilja Gerhardt

00

20

40

6 0

80

10 0

E-fie

ld [a.

u.]

Exp erim en t Sim u lation

20 0Laser D etu n in g [M H z]

-20 0 0 20 0-20 0

Frequency Dependence

Phys. Rev. A 79, 011402(R) (2009)

Ilja Gerhardt

Results & Summary• Short Pulse Experiments with a Single

Molecule–First measurements on a single molecule

• Time resolved mode–Similar to Autocorrelation, nice way to determine

T1 and T2• Integrated mode–Up to 10 p oscillations (max. in solid state)–First detuning dependent data

• First extinction measurements (not shown)

• Aiming for coherent control – phase gate

(?)

Ilja Gerhardt

What’s next?• Single Photon Source• Detector efficiency

• More Extinction• Imaging• Single Molecule Switch (2nd

Laser)

Ilja Gerhardt

Thanks for Your Attention