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The Shot Noise Thermometer

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Shot Noise. Conduction in Tunnel Junctions. Assume: Tunneling ... Determine effect of nonlinearity on shot noise. Measure heating effects with dirty film ... – PowerPoint PPT presentation

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Title: The Shot Noise Thermometer


1
The Shot Noise Thermometer
  • Lafe Spietz, K.W. Lehnert,
  • I. Siddiqi, R.J. Schoelkopf
  • Department of Applied Physics, Yale University
  • Thanks to
  • Michel Devoret, Daniel E. Prober, and Wes Tew



2
Introduction
  • Johnson-Schottky transition of the noise in
    tunnel junctions
  • Relates T and V using only e and kB
  • ? primary thermometer
  • Demonstrate operation from T0.02 K to 300 K

Lafe Spietz et al, Science 300, 1929 (2003)
3
Thermometry
Desirable Characteristics for a Thermometer
  • Wide Range
  • Fast
  • Primary
  • Accurate
  • Easy and simple to use
  • Physically compact

Secondary Needs to be calibrated from some
outside standard, e.g. resistive thermometers
Primary Needs no outside calibrationbased on
understood physics, e.g. ideal gas thermometer
4
Cryogenic Thermometry Overview
300 K
100 K
Johnson Noise
Resistance Thermometers
10 K
1 K
RuOx
50 mK
CBT
0.1 K
3He Melting Curve
0.01 K
Nuclear Orientation
5
Fundamental Noise Sources
  • Johnson-Nyquist Noise
  • Frequency-independent
  • Temperature-dependent
  • Used for thermometry

Shot Noise
  • Frequency-independent
  • Temperature independent

6
Conduction in Tunnel Junctions
Difference gives current
Fermi functions
Assume Tunneling amplitudes and
D.O.S. independent of energy Fermi
distribution of electrons
Conductance (G) is constant
7
Thermal-Shot Noise of a Tunnel Junction
Sum gives noise
D. Rogovin and D.J. Scalpino, Ann Phys. 86,1
(1974)
8
Thermal-Shot Noise of a Tunnel Junction
2eI Shot Noise
4kBT
Transition Region eVkBT
Johnson Noise
R
9
Self-Calibration Technique
P(V) Gain( SIAmpSI(V,T) )
P(V)

V
10
Experimental Setup RF DCMeasurement
P
5m
SEM
Al-Al2O3-Al Junction
11
High-Bandwidth Measurement
t 1 second
12
Noise Versus Voltage
13
Universal Functional Form
Agreement over four decades in temperature
14
Comparison With Secondary Thermometers
15
High Precision Measurement
Residuals
16
Uncertainty vs. Integration Time
17
Thermodynamic Uncertainties of Temperature Scales
Thermodynamic Uncertainty of PLTS-2000
500 mK
SNT
18
High Bias Nonidealities
High Bias
High T
19
Nonlinear Current and Noise
20
Modular SNT Package
Copper Tubing for DC lines
Copper Plumbing parts
Tunnel Junction
SMA Connectors for RF
Built-in Bias Tee (on-board SMT Components)
Total cost of package lt10
21
Future Work
  • Determine effect of nonlinearity on shot noise
  • Measure heating effects with dirty film
  • Improve room temperature results
  • Measure hydrogen triple point
  • Make SNT more modular and easy to use for use in
    other labs and for commercialization
  • Push the lower temperature end with lower system
    noise temperature and more careful filtering

22
Summary
  • Demonstrate functional form of junction
    noise 0.02 - 300 Kelvin
  • Use as fast, accurate thermometer
  • As good as 200 ppm precision, 0.1 accuracy
  • Relates T to V using only e and kB Possible
    kB determination?

Lafe Spietz et al, Science 300, 1929 (2003)
23
END
24
Tien-Gordon Theory
Tucker and Feldman, 1985
25
Tien-Gordon for Noise of Junction
26
(No Transcript)
27
Diode Nonlinearity
Vdiode GP bG2P2
b -3.1 V-1
1mV gt 3x10-3 fractional error
28
Conductance
R31.22Ohms
29
More Conductance
30
Fano Factor Has No Effect
31
Correlations of Fit Parameters
32
Null-Balancing Noise Measurement for High
Precision
Noise Contours in Voltage-Space
Small range of noise keeps detector in linear
range
33
Temperature Measurements Over Time
34
Experimental SetupRF DCMeasurement and
Thermometry
RhFe Thermometer
capacitors
device
RuOx Thermometer
inductors
35
Fit With Two Parameters
Residuals
36
Merits Vs. Systematics
Merits
  • Systematics
  • I-V curve nonlinearities
  • Amplifier and diode nonlinearities
  • Frequency dependence
  • Self-heating
  • Fast and self-calibrating
  • Primary
  • Wide T range
  • (mK to room temperature)
  • No B-dependence
  • Compact electronic sensor
  • Possibility to relate T to frequency!

R. J. Schoelkopf et al., Phys Rev. Lett. 80,
2437 (1998)
37
Tunnel Junction(AFM image)
R33 W Area10 mm2
Al-Al2O3-Al Junction
V
I
I-
V-
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