Presentation is loading. Please wait.

Presentation is loading. Please wait.

The Ideal Electron Gas Thermometer

Similar presentations


Presentation on theme: "The Ideal Electron Gas Thermometer"— Presentation transcript:

1 The Ideal Electron Gas Thermometer
R.J. Schoelkopf, Lafe Spietz, K.W. Lehnert, I. Siddiqi Department of Applied Physics, Yale University Thanks to: Michel Devoret and Daniel E. Prober

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 T=0.02 K to 300 K

3 Fundamental Noise Sources
Thermal(Johnson) Noise Frequency-independent Temperature-dependent Used for thermometry Shot(Schottky) Noise Frequency-independent Temperature independent

4 Conduction in Tunnel Junctions
M I M Difference gives current: Fermi functions Assume: Tunneling amplitudes and D.O.S. independent of energy Fermi distribution of electrons Conductance (G) is constant

5 Thermal-Shot Noise of a Tunnel Junction*
Sum gives noise: *D. Rogovin and D.J. Scalpino, Ann Phys. 86,1 (1974)

6 Thermal-Shot Noise of a Tunnel Junction
2eGV=2eI Shot Noise Johnson-Schottky Transition Region eV~kBT 4kBT Thermal Noise R

7 Johnson-Schottky Transition:
Direct relationship between T and V

8 Tunnel Junction (AFM image)
R=33 W Area=10 mm2 Al-Al2O3-Al Junction V+ I+ I- V-

9 Experimental Setup:RF + DC Measurement

10 Experimental Setup:RF + DC Measurement and Thermometry
RhFe Thermometer capacitors device RuOx Thermometer inductors

11 Experimental Setup: Pumped He Cryostat
Noise power vs. bias voltage: High bandwidth: hence fast For t = 1 second,

12 Self-Calibration Technique for Thermometry
Subtract offsets P = Gain*B( SIAmp+SI(V,T) )

13 Self-Calibration Technique for Thermometry
Slope = 2eGB/R -GB(4kBT/R)

14 Noise Versus Voltage

15 Universal Functional Form: Agreement over four decades In temperature

16 Comparison With Secondary Thermometers

17 Temperature Measurements Over Time

18 Uncertainty vs. Integration Time

19 Fit With Two Parameters
Residuals

20 Fit With Three Parameters
Residuals

21 Correlations of Fit Parameters

22 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)

23 Summary Ideal Electron Gas Thermometer based on Johnson-Schottky transition of noise in a tunnel junction (thermal-shot noise.) Fast, accurate, primary thermometer Works over a wide temperature range Relates T to V using only e and kb applications for metrology

24 Tien-Gordon Theory Tucker and Feldman, 1985

25 Tien-Gordon for Noise of Junction

26

27 Diode Nonlinearity Vdiode = GP + bG2P2 b= -3.1 V-1
1mV => 3x10-3 fractional error

28 Conductance R=31.22Ohms

29 More Conductance

30 2 3 1 4


Download ppt "The Ideal Electron Gas Thermometer"

Similar presentations


Ads by Google