Title: The Shot Noise Thermometer
1The 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
2Introduction
- 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)
3Thermometry
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
4Cryogenic 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
5Fundamental Noise Sources
- Johnson-Nyquist Noise
- Frequency-independent
- Temperature-dependent
- Used for thermometry
Shot Noise
- Frequency-independent
- Temperature independent
6Conduction 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
7Thermal-Shot Noise of a Tunnel Junction
Sum gives noise
D. Rogovin and D.J. Scalpino, Ann Phys. 86,1
(1974)
8Thermal-Shot Noise of a Tunnel Junction
2eI Shot Noise
4kBT
Transition Region eVkBT
Johnson Noise
R
9Self-Calibration Technique
P(V) Gain( SIAmpSI(V,T) )
P(V)
V
10Experimental Setup RF DCMeasurement
P
5m
SEM
Al-Al2O3-Al Junction
11High-Bandwidth Measurement
t 1 second
12Noise Versus Voltage
13Universal Functional Form
Agreement over four decades in temperature
14Comparison With Secondary Thermometers
15High Precision Measurement
Residuals
16Uncertainty vs. Integration Time
17Thermodynamic Uncertainties of Temperature Scales
Thermodynamic Uncertainty of PLTS-2000
500 mK
SNT
18High Bias Nonidealities
High Bias
High T
19Nonlinear Current and Noise
20Modular 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
21Future 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
22Summary
- 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)
23END
24Tien-Gordon Theory
Tucker and Feldman, 1985
25Tien-Gordon for Noise of Junction
26(No Transcript)
27Diode Nonlinearity
Vdiode GP bG2P2
b -3.1 V-1
1mV gt 3x10-3 fractional error
28Conductance
R31.22Ohms
29More Conductance
30Fano Factor Has No Effect
31Correlations of Fit Parameters
32Null-Balancing Noise Measurement for High
Precision
Noise Contours in Voltage-Space
Small range of noise keeps detector in linear
range
33Temperature Measurements Over Time
34Experimental SetupRF DCMeasurement and
Thermometry
RhFe Thermometer
capacitors
device
RuOx Thermometer
inductors
35Fit With Two Parameters
Residuals
36Merits 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)
- Compact electronic sensor
- Possibility to relate T to frequency!
R. J. Schoelkopf et al., Phys Rev. Lett. 80,
2437 (1998)
37Tunnel Junction(AFM image)
R33 W Area10 mm2
Al-Al2O3-Al Junction
V
I
I-
V-