Calorimetry and finite bath thermodynamics Jukka Pekola, Low Temperature Laboratory Aalto University, Helsinki, Finland
Calorimetry for measuring the photons Requirements for calorimetry on single microwave quantum level. Photons from relaxation of a superconducting qubit. Typical parameters: Operating temperature T = 0.1 K E/k B = 1 K, C = k B T ~ mK, ~ ms NET = 10 K/(Hz) 1/2 is sufficient for single photon detection E = NET (C G th ) 1/2 JP, P. Solinas, A. Shnirman, and D. V. Averin., NJP 15, (2013). T = E / C = C / G th E photon source “artificial atom” absorber temperature readout electronics T(t) V(t)
Fast NIS thermometry on electrons Read-out at 600 MHz of a NIS junction, 10 MHz bandwidth S. Gasparinetti et al., Phys. Rev. Applied 3, (2015); K. L. Viisanen et al., New J. Phys. 17, (2015). Proof of the concept: Schmidt et al., 2003
Josephson thermometer (at 5 GHz) O.-P. Saira, M. Zgirski, D. Golubev, K. Viisanen and JP, arXiv: (2016).arXiv: P(E) theory: Only one fit parameter: R S = 57.4 .
Josephson thermometer (at 5 GHz) Expected 1 K photon resolution
Towards calorimetry of a superconducting qubit J. Senior, O.-P- Saira et al., 2016
Measurement of thermal coupling G th and heat capacity C of a normal wire E = NET (C G th ) 1/2 Copper and silver thin film wires measured K. L. Viisanen and JP, in preparation (2016).
G th - electron-phonon coupling T (K) Cu = 2 GW/m 3 K 5 in literature Ag = 0.5 GW/m 3 K 5 inferred from data of A. Steinbach et al., PRL 1996
Heat capacity C |s 21 | 2 (arb) T bath C,T G th C of copper films is anomalously high (x10) Silver follows free-electron Fermi-gas model C = ( 2 /3) N(0)k B 2 V T
Calorimetry on quantum two-level systems: ”errors” 1. Hidden environments/noise sources K. L. Viisanen et al., New J. Phys. 17, (2015). 2. Finite heat capacity of the absorber (non-Markovian) TEMPERATURE TIME T0T0 E T(t) V(t)
Fluctuating energy of a finite bath TT TIME T C, E, T ? !
(a) (b) (c) QUBIT TLS- CALORIMETER HO- CALORIMETER TLS- CALORIMETER TLS-BATH DRIVE Simple models of a finite calorimeter J. P. Pekola, S. Suomela, and Y. M. Galperin, arXiv: , J. Low Temp. Phys. (2016). arXiv: J. Low Temp. Phys See also: S. Suomela, A. Kutvonen, T. Ala- Nissila, arXiv: arXiv:
TLS calorimeter and bath: equal level spacing and coupling
Quantum jump trajectories F. Hekking and JP, PRL 111, (2013); J. Horowitz and J. Parrondo, NJP 15, (2013); JP, Y. Masuyama, Y. Nakamura, J. Bergli, and Y. M. Galperin, PRE 91, (2015). Stochastic wave function of the qubit Qubit rates Calorimeter rates Evolution of the qubit state when no jumps occur
Initially: Population of the calorimeter at the end of the drive is enhanced. This has naturally no effect on the fluctuation relations. Overheating of the calorimeter
Distributions of work, Crooks relation Qubit + calorimeter only Initially thermalized Qubit + calorimeter + big bath Initially thermalized Blue – all heat included Black – heat to big bath ignored Line: P(W)/P(-W)=e W G. Crooks, 1999
More realistic model: resistor bath (free Fermi-gas) E T(t) V(t) For an Ag wire with V = m 3 at T = 100 mK, C/k B < 100 T/T F = Energy fluctuations become strongly non- gaussian in this regime JP, P. Muratore-Ginanneschi, A. Kupiainen, and Yu. M. Galperin, arXiv: arXiv: Analysis of equilibrium energy fluctuations for a free-electron gas with finite heat capacity T C, E
Calculation of the energy distribution
Equilibrium energy distribution Gaussian E 0 corresponds to filled Fermi-sea
Summary Metallic calorimeters are just about sensitive enough to monitor single microwave photons Fast thermometry and qubit in a cavity tested Anomalous heat capacity of copper vs silver observed Physics of finite heat capacity absorber discussed – work in progress
Collaboration Olli-Pentti Saira (AALTO) Klaara Viisanen (AALTO) Simone Gasparinetti (AALTO, now ETH) Jorden Senior (AALTO) Joonas Peltonen (AALTO) Matthias Meschke (AALTO) Maciej Zgirski (Warsaw) Dmitry Golubev (AALTO) Yuri Galperin (Oslo) Frank Hekking (Grenoble) Joachim Ankerhold (Ulm) Paolo Muratore-Ginanneschi (Univ. Helsinki) Antti Kupiainen (Univ. Helsinki) Samu Suomela (AALTO) Tapio Ala-Nissila (AALTO) Kay Schwieger (Univ. Helsinki)