Quantum state detection of a superconducting flux qubit using a dc-SQUID in the inductive mode

We present a readout method for superconducting flux qubits. The qubit quantum flux state can be measured by determining the Josephson inductance of an inductively coupled dc superconducting quantum interference device sdc-SQUIDd. We determine the response function of the dc-SQUID and its back-action on the qubit during measurement. Due to driving, the qubit energy relaxation rate depends on the spectral density of the measurement circuit noise at sum and difference frequencies of the qubit Larmor frequency and SQUID driving frequency. The qubit dephasing rate is proportional to the spectral density of circuit noise at the SQUID driving frequency. These features of the back-action are qualitatively different from the case when the SQUID is used in the usual switching mode. For a particular type of readout circuit with feasible parameters we find that single shot readout of a superconducting flux qubit is possible.

[1]  I. Chuang,et al.  Quantum Computation and Quantum Information: Bibliography , 2010 .

[2]  S. Girvin,et al.  Strong coupling of a single photon to a superconducting qubit using circuit quantum electrodynamics , 2004, Nature.

[3]  P. Hakonen,et al.  Inductive single-electron transistor. , 2004, Physical Review Letters.

[4]  L Frunzio,et al.  An RF-Driven Josephson Bifurcation Amplifier for Quantum Measurements , 2003, cond-mat/0312623.

[5]  A. Lupascu,et al.  Nondestructive readout for a superconducting flux qubit. , 2003, Physical review letters.

[6]  Yuriy Makhlin,et al.  Dephasing of solid-state qubits at optimal points. , 2003, Physical review letters.

[7]  John M. Martinis,et al.  Banishing quasiparticles from Josephson-junction qubits: why and how to do it , 2003 .

[8]  A. Smirnov.  Theory of weak continuous measurements in a strongly driven quantum bit , 2003, cond-mat/0306004.

[9]  T. Duty,et al.  Coherent dynamics of a Josephson charge qubit , 2003, cond-mat/0305433.

[10]  H. E. Hoenig,et al.  Low-frequency measurement of the tunneling amplitude in a flux qubit , 2003, cond-mat/0303657.

[11]  John M. Martinis,et al.  Decoherence of a superconducting qubit due to bias noise , 2003 .

[12]  Yasunobu Nakamura,et al.  Coherent Quantum Dynamics of a Superconducting Flux Qubit , 2003, Science.

[13]  Yu. A. Pashkin,et al.  Quantum oscillations in two coupled charge qubits , 2002, Nature.

[14]  J. E. Mooij,et al.  Engineering decoherence in Josephson persistent-current qubits , 2002, cond-mat/0211664.

[15]  J. Martinis,et al.  Rabi oscillations in a large Josephson-junction qubit. , 2002, Physical review letters.

[16]  Siyuan Han,et al.  Coherent Temporal Oscillations of Macroscopic Quantum States in a Josephson Junction , 2002, Science.

[17]  M. Devoret,et al.  Manipulating the Quantum State of an Electrical Circuit , 2002, Science.

[18]  Y. Makhlin,et al.  Noise and Decoherence in Quantum Two-Level Systems , 2002, cond-mat/0202518.

[19]  A. Zorin.  Cooper-pair qubit and Cooper-pair electrometer in one device , 2001, cond-mat/0112351.

[20]  John Clarke,et al.  Superconducting quantum interference device as a near-quantum-limited amplifier at 0.5 GHz , 2001 .

[21]  A. Zorin,et al.  Radio-frequency Bloch-transistor electrometer. , 2000, Physical review letters.

[22]  F K Wilhelm,et al.  Quantum superposition of macroscopic persistent-current states. , 2000, Science.

[23]  D. Averin,et al.  Continuous weak measurement of quantum coherent oscillations , 2000, cond-mat/0002203.

[24]  Seth Lloyd,et al.  Superconducting persistent-current qubit , 1999, cond-mat/9908283.

[25]  Orlando,et al.  Josephson Persistent-Current Qubit , 2022 .

[26]  Y. Pashkin,et al.  Coherent control of macroscopic quantum states in a single-Cooper-pair box , 1999, Nature.

[27]  R. F. Bradley,et al.  Cryogenic, low-noise, balanced amplifiers for the 300–1200 MHz band using heterostructure field-effect transistors , 1999 .

[28]  Clarke,et al.  Measurements of macroscopic quantum tunneling out of the zero-voltage state of a current-biased Josephson junction. , 1985, Physical review letters.

[29]  A. Barone,et al.  Physics and Applications of the Josephson Effect , 1982 .