Denis Konstantinov, Leonid Abdurakhimov, William Powell Development of a cryogenic spectrometer for experiments with electrons on helium Electrons on Helium 2014, Kazan, May 3-7 Quantum Dynamics Unit, OIST Graduate University
Denis Konstantinov, Leonid Abdurakhimov,
William Powell
Development of a cryogenic spectrometer
for experiments with electrons on helium
Electrons on Helium 2014, Kazan, May 3-7
Quantum Dynamics Unit, OIST Graduate University
Cryogenic Lab.
Quantum Dynamics Unit
OIST Graduate University
Okinawa Institute of Science and Technology - OIST
One of the goals – development of
Collaborartion with Sergey Vasiliev, Turku
a cryogenic spectrometer for ESR
- Nonliner NMR in solid antiferromagnets
Other activities
Magneto-transport under excitation -
Collaboartion with Yu. Bunkov, CNRS Grenoble
Talks by A. Badrutdinov and L. Abdurakhimov
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
T=740 mK -25 dBm
-20 dBm
-15 dBm
-10 dBm
-5dBm
0 dBm
5 dBm
10 dBm
15 dBm
18 dBm
4Q
B0 (T)
Electron transport through constriction -
Collaboration with David Rees
- Spectroscopy of surface and spin states
- Fabry-Perot cavities, preliminary experiments
Talk (Part 1)
(D. Konstantinov)
(W. Powell)
Standard method
MW
+ VB
InSb
fref
PSD
mod
B
signal δVV
AδV
VB
δVmod
δVsignal
Grimes and Brown, PRL 1974
Collin et al., PRL 2002
Previous experiments in RIKEN
H. Isshiki, DK et al. J. Phys. Soc. Jpn. 2008
Power absorption
22
0
2
21)(
5.0)(
nnPa
Asymmetric “Fano” shape
Photo-induced phenomena in transport
- Bistabiliti and hysteresis
- Photo-conductivity and electron heating
DK at al. PRL 2009
DK et al. PRB 2012
DK and Kono, PRL 2009, PRL 2010
DK at al, PRL 2013
DK et al. PRL 2007
- Magneto-transport and ZRS
90 95 100
0.4
0.5
0.6
0.7
F (V/cm)
-1 (
M
)
T=0.5 K
4 5 6 7 8 90
5
10
15
xx (
10
-11
-1)
/c
Electron spins on liquid helium
[S. A. Lyon, Phys. Rev. A, 74,
052338]
Trap
[D. I. Shuster et al. PRL 105, 040503
(2010)]
- Spin qubits with long coherence time (S. Lyon)
- c-QED and SC-spin hybrid system (D. Shuster et al.)
- Multi-spin system for quantum memory storage
Spin resonance?
Power absorption
2
2
0
2
221
)(1
5.0)(
T
TnnPa
1HB - Rabi frequency
High MW power
2TNPa
- absorption saturation
Absorption saturation
E1
E2
E1
E2
E1
E2
121 /1 TA 12B 21B
µV 1TNPa
Absorption signal from 107 electrons
s 7
1 10T - for surface states
s 2
1 10T - for spin states
DK and Kono, J. Phys. Soc. Jpn. 2013 Need 1015 electrons!
Reflection from cavity
cavity
detector
Z0 C
L
R
0
0
ZZ
ZZ
V
V
L
L
in
out
Reflection coefficient -
Effect of sample - )41( LL
jQ
jQ
L
L
41
)1(4 1
0
0
0
Pin
Power the detector -
in
L
L PjQ
jQP
2
det41
4
jwhere
Reflection from cavity
jAt the resonance
in
Le
L PQTTH
QP
2
''
max21
2
1
2
''
maxdet
41
4
From Bloch equations 21
2
1
2200
21
2
1
2
''
max
1
1
2
1
1 TTHT
TTH ee
s 10021 TT
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
1012
cm-2
1011
cm-2
1010
cm-2
Pd
et (
pW
)
Pin (pW)
109 cm
-2
Q=10 000
Use theoretical estimate
Heterodyne detection
S. Vasiliev et al. Rev. Sci. Instrum. 75, 94 (2004)
- Cryogenic mixers
conversion losses 10 dB
noise temperature 100 K
- Fabry-Perot resonator
- Down-conversion to 100 MHz
Spectroscopy of surface states
Z0
C L R 0
0
ZZ
ZZ
V
V
L
L
in
out
Reflection coefficient -
Effect of sample - )41( eCC
where electrical susceptibility EED e4
Electrical dipole moment 222221121111
2121)()( zeeztezttjtj
2
1
22
0
)(
0*
2112
2
1
22
0
2
11122
)(
))((
2
1
)(1
0
T
ej
T
T
tj
From optical Bloch equations
Reflection from cavity
2
1
22
0
2
12''
2
1
22
0
02
12'
)(
)(
)(
)()(
T
ezn
T
ezn
e
e
Complex electrical susceptibility
in
L
L PQT
QP
2
''
max
21
1
''
maxdet
41
4
s 7
1
1 10 T
100
101
102
103
104
105
10-3
10-2
10-1
100
101
102
103
104
105
108 cm
-2
107 cm
-2
106 cm
-2
Pd
et (
pW
)
Pin (pW)
105 cm
-2
Q=10 000
A. Badrutdinov et al. Eur. Phys. Lett. 2013
Use experimental estimate
Back to asymmetric “Fano” shape
H. Isshiki, DK et al. J. Phys. Soc. Jpn. 2008
Asymmetric “Fano” shape
)( '''
det eeel
j
refoutelrefout jVeVVVVVV
2'''
det )(1 ee
j jeP - mixture of absorption
and dispersion response
H. Isshiki, DK et al. J. Phys. Soc. Jpn. 2008
“Fano” lineshape
“Mixture” lineshape
22
0
0
)(
)(sin)cos1()(
F
13 14 15 16
-10
0
10
20
30 4He: T=900 mK
VInSb
=20-35 mV
160.99 GHz
160.9 GHz
159.9 GHz
V (V
)
Vbottom
(V)
159.5 GHz
GHz 85.024
1 f
Lf
Back to asymmetric “Fano” shape
24 26 28 30 32
-2
-1
0
1
fitting
dA
/dE
(a
rb.
un
it)
bias voltage VB (V)
620 mK
Changes with frequency (test of the model)
Good agreement!
Talk (Part 2)
- Spectroscopy of surface and spin states
- Fabry-Perot cavities, preliminary experiments
(D. Konstantinov)
(W. Powell)
Fabry-Perot resonator
coupling hole
spacer for frequency
adjustment
spherical mirrors
• Spectrometer uses bandpass filter
centered at 140 GHz
• Aim to tune resonance frequency to this
value
• Take into account dependence on
temperature and presence of dielectric in
cavity
• First, identify modes
Fabry-Perot resonator
• Modes given by
• Easier to identify if we consider only
TEM00 modes
• Achieved experimentally by placing
electrode within resonator cavity
Cavity modes
Cavity size (m)
Res
on
an
t fr
eq
ue
ncy (
Hz)
Cavity modes
Cavity Size (m)
Res
on
an
t fr
eq
ue
ncy (
Hz)
TEM00 modes
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
134 136 138 140 142 144 146
Sig
nal
(V)
Frequency (GHz)
Resonator Modes - Closed vs Open Geometry
Closed Geometry
Open Geometry
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
134 136 138 140 142 144 146
Sig
nal
(V)
Frequency (GHz)
Effect of Electrode on Resonator Modes
Electrode Present
Electrode Missing
Cavity Size (m)
Res
on
an
t fr
eq
ue
ncy (
Hz)
TEM00 modes
• Cooling reduces size of resonator cavity
increasing resonant frequency of modes
• Tested at liquid nitrogen temperature
• Observed 500 MHz shift in resonant
frequency
Working mode
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
0.05
139.5 140 140.5 141 141.5 142 142.5
Sig
nal
(V)
Frequency (GHz)
Effect of Cooling on Resonator Modes
Uncooled Resonator
Cooled Resonator
• Difficult to determine effect of dielectric
• Naïve approximation expect to see
resonance somewhere between cavity full
of dielectric and empty
• Calculated to fall roughly 3 GHz
Working mode
0
0.002
0.004
0.006
0.008
0.01
0.012
134 136 138 140 142 144 146
Sig
nal
(V)
Frequency (GHz)
Tuning Size of Resonator Cavity
4.43mm Spacer
4.34mm Spacer
4.30mm Spacer
0.00E+00
5.00E-05
1.00E-04
1.50E-04
2.00E-04
2.50E-04
143.4 143.45 143.5 143.55 143.6 143.65 143.7 143.75 143.8
Bo
lom
ete
r S
ign
al
(V)
Frequency (GHz)
Resonance shift and QF drop
1.15E-01
1.15E-01
1.16E-01
1.16E-01
1.17E-01
1.17E-01
1.18E-01
1.18E-01
1.19E-01
143.55 143.6 143.65 143.7 143.75 143.8 143.85 143.9 143.95
Bo
lom
ete
r S
ign
al
(V)
Frequency (GHz)
Resonance before He Condensation
• In fridge see small drop in resonant
frequency and large decrease in quality
factor
• Fixing frequency at resonance and
sweeping pressing field brings electrons
into resonance
• Derivative of absorption signal detected
using lock-in amp
Working mode
0
0.000002
0.000004
0.000006
0.000008
0.00001
0.000012
0.000014
0 5 10 15 20 25 30 35
Bo
lom
ete
r S
ign
al
(V)
Electrode Voltage (V)
Signal of electrons at cavity resonance frequency
• Unusual noise appears when TBS vacuum
pump is attached to cell
• Noise depends on level of liquid Helium
• Mechanical vibration caused by vibrating
liquid Helium?
Opto-mechanical effect
1.15E+00
1.15E+00
1.15E+00
1.16E+00
1.16E+00
1.16E+00
1.16E+00
1.16E+00
1.17E+00
143.4 143.45 143.5 143.55 143.6 143.65 143.7 143.75 143.8
Bo
lom
ete
r S
ign
al
(V)
Frequency (GHz)
Noise from Turbo-pump System
1.15E+00
1.15E+00
1.15E+00
1.16E+00
1.16E+00
1.16E+00
1.16E+00
1.16E+00
1.17E+00
143.4 143.45 143.5 143.55 143.6 143.65 143.7 143.75 143.8
Bo
lom
ete
r S
ign
al
(V)
Frequency (GHz)
Cavity Resonance SIgnal
1.37E+00
1.38E+00
1.39E+00
1.40E+00
1.41E+00
1.42E+00
1.43E+00
1.44E+00
1.45E+00
1.46E+00
141 141.5 142 142.5 143 143.5 144 144.5
Bo
lom
ete
r S
ign
al
(V)
Frequency (GHz)
Reducing Helium level Reduces TBS Noise
1.35E+00
1.36E+00
1.37E+00
1.38E+00
1.39E+00
1.40E+00
1.41E+00
1.42E+00
1.43E+00
141 141.5 142 142.5 143 143.5 144 144.5
Bo
lom
ete
r S
ign
al
(V)
Frequency (GHz)
1.34E+00
1.35E+00
1.36E+00
1.37E+00
1.38E+00
1.39E+00
1.40E+00
1.41E+00
141 141.5 142 142.5 143 143.5 144 144.5
Bo
lom
ete
r S
ign
al
(V)
Frequency (GHz)
- Heterodyne detection of ESR in electrons on
Summary
- Can be useful for studying D1-transitions as well
- Employment of open Fabry-Perot resonators
helium is under development
could be useful