01/09/2014 1 subnanosecond spectral diffusion of a single quantum dot in a nanowire g. sallen, a....
TRANSCRIPT
11/04/23
www.neel.cnrs.fr
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Subnanosecond spectral diffusionof a single quantum dot in a nanowire
G. Sallen, A. Tribu, T. Aichele*, R. André, L. Besombes,C. Bougerol, M. Richard, S. Tatarenko, K. Kheng, and J.-Ph. Poizat
CEA/CNRS/UJF joint team "Nanophysics and semi-conductors"Institut Néel and INAC, Grenoble, France
* Present address :Physics Institute, Humboldt University, Berlin, Germany
11/04/23
www.neel.cnrs.fr
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Spectral diffusion
Random spectral jumps of a narrow lineas a result of fluctuating environment
Described by two parameters : diffusion amplituded : diffusion time
2.3322.3302.328Energy (eV)
d < : motional narrowing(dephasing)Lorentzian lineshape
A. Berthelot et al, Nat Phys (2006)
d > : wandering line :Gaussian lineshape
Besombes et al, PRB (2002)
Spectral diffusion of a single emitter
Standard method :Record spectra time serieTime resolution > 1 ms
* Resonant excitation of afluctuating line, photon correlationon the luminescence.Time resolution > 1µsZambusch et al, PRL (1993)
* Photon-correlation Fourierspectroscopy.Time resolution > 20 µsCoolen et al, PRL (2008)
Alternative methods :
Our method
Photon correlations on parts of the line :
Best time resolution : 90 ps
W holeLine
d
H s ide
L s ide
C X
2.3302.3282.326Energy (eV)
L side H sidet
t
t
1
0
g(2
) CX(L
,H,
)
-20 -10 0 10 20Delay (ns)
1
0g(2
) CX(L
,L,
)
2
1
0
g(2
) CX(
) c)
d)
e)
d
CX
Whole lineauto-correlation
L sideAuto-correlation
L- Hcross-correlation
Results
W holeLine
d
H s ide
L s ide
C X
2.3302.3282.326Energy (eV)
L side H sidea)
b)
t
t
t
Slow detectors : time resolution = 800ps
1.2
1.0
0.8
0.6
0.4
0.2
0.0
g(2) (L
,H,
)
-10 0 10Delay (ns)
2.3302.325Energy (eV)
2.3302.325Energy (eV)
Robustness with respect to energy slot size
Cross-correlation
The cross-correlation does not depend on the size of the energy slots
2.3302.327Energy (eV)
2.3302.327Energy (eV)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
g(2) (L
,H,
)
-10 0 10Delay (ns)
Robustness with respect to energy separation
The probability of a spectral jump does not depend on its amplitude
Cross-correlation
~ 400 nm
~ 10 nm
Our sample
Single CdSe quantum dot inserted in a ZnSe nanowire
2.342.332.32Energy (eV)
XX
CX
X
Lifetimes : X = 500 ps CX = 650 ps CX = 450 ps
Antibunching @ T=220K : Tribu et al, NanoLett (2008)
Photon correlation spectroscopy : Sallen et al, PRB (2009)
1.5
1.4
1.3
1.2
1.1
1.0Line
wid
th (
meV
)
302520151050Excitation power (µW)
0.6
0.4
0.2
0.0
Diff
usi
on r
ate
(ns-1
)
Diffusion rate vs excitation power
T=4K
T=10K
CX to X diffusion rate
Spectral diffusion of theCX line (T=4K, T=10K)
10K/4K => Etrap= 1.1 meV
Linewidth = cste => Single charge exploring the traps
PCXsat
Spectral diffusion possible scenario
Conductionband
QD
1.1 meV
ZnSe CdSe ZnSe
10 nm
~3 nm
5
4
3
2
1
0
g(2
) X-X
X(L
,H,
)
-4 -2 0 2 4 Delay (ns)
5
4
3
2
1
0
g(2
) X-X
X(H
,H,
)
2.2362.234E (eV)
2.2182.2162.214E (eV)
2.2362.234 E (eV)
2.2182.2162.214E (eV)
XX
X
XX
X
Cascadepeak
2.2402.2302.2202.210Energy (eV)
XXCX
X
The sign of the energy shiftinduced by the fluctuatingenvironment is the sameon X and XX.
Correlated spectral diffusion
XX
X
Fast detectors : time resolution= 90ps
Conclusions
* Simple and robust method to measure spectral diffusionwith 90 ps resolution
(4 orders of magnitude improvementcompared to best existing resolution).
* Spectral duration time gives the under whichthere is no spectral diffusion.
* Opens new possibilities for the investigation of the very localenvironnement of single emitters.