1
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Intrinsic and induced quantum quenches for enhancing qubit-based quantum noise spectroscopy. Nat Commun 2021; 12:6528. [PMID: 34764276 PMCID: PMC8586144 DOI: 10.1038/s41467-021-26868-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 10/26/2021] [Indexed: 11/18/2022] Open
Abstract
Quantum sensing protocols that exploit the dephasing of a probe qubit are powerful and ubiquitous methods for interrogating an unknown environment. They have a variety of applications, ranging from noise mitigation in quantum processors, to the study of correlated electron states. Here, we discuss a simple strategy for enhancing these methods, based on the fact that they often give rise to an inadvertent quench of the probed system: there is an effective sudden change in the environmental Hamiltonian at the start of the sensing protocol. These quenches are extremely sensitive to the initial environmental state, and lead to observable changes in the sensor qubit evolution. We show how these new features give access to environmental response properties. This enables methods for direct measurement of bath temperature, and for detecting non-thermal equilibrium states. We also discuss how to deliberately control and modulate this quench physics, which enables reconstruction of the bath spectral function. Extensions to non-Gaussian quantum baths are also discussed, as is the application of our ideas to a range of sensing platforms (e.g., nitrogen-vacancy (NV) centers in diamond, semiconductor quantum dots, and superconducting circuits).
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2
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Mao H, Jin J, Wang S, Yan Y. Nonequilibrium Kondo regime current noise spectrum of quantum dot systems with the single impurity Anderson model. J Chem Phys 2021; 155:014104. [PMID: 34241380 DOI: 10.1063/5.0045346] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the nonequilibrium current noise spectrum of single impurity Anderson model quantum dot systems on the basis of the accurate dissipation equation of motion evaluations. By comparing between the equilibrium and nonequilibrium cases and between the non-Kondo and Kondo regimes, we identify the current noise spectrum of the nonequilibrium Kondo features that actually appear in the entire region of ω ∈ [-eV, eV]. It is well known that the primary Kondo characteristics at ω = ±eV = ±(μL - μR) display asymmetrical upturns and remarkable peaks in S(ω) and dS(ω)/dω, respectively. These features are originated from the Rabi interference of the transport current dynamics, with the Kondo oscillation frequency of |eV|. Moreover, we also identify the minor but very distinguishable inflections, crossing over from ω = -eV to ω = +eV. This uncovered feature would be related to the interference between two Kondo resonance channels.
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Affiliation(s)
- Hong Mao
- Department of Physics, Hangzhou Normal University, Hangzhou, Zhejiang 311121, China
| | - Jinshuang Jin
- Department of Physics, Hangzhou Normal University, Hangzhou, Zhejiang 311121, China
| | - Shikuan Wang
- Department of Physics, Hangzhou Dianzi University, Hangzhou 310018, China
| | - YiJing Yan
- Hefei National Laboratory for Physical Sciences at the Microscale & i ChEM, University of Science and Technology of China, Hefei, Anhui 230026, China
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3
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Février P, Gabelli J. Tunneling time probed by quantum shot noise. Nat Commun 2018; 9:4940. [PMID: 30467389 PMCID: PMC6250673 DOI: 10.1038/s41467-018-07369-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 10/25/2018] [Indexed: 11/08/2022] Open
Abstract
In typical metallic tunnel junctions, the tunneling events occur on a femtosecond timescale. An estimation of this time requires current measurements at optical frequencies and remains challenging. However, it has been known for more than 40 years that as soon as the bias voltage exceeds one volt, the junction emits infrared radiation as an electrically driven optical antenna. We demonstrate here that the photon emission results from the fluctuations of the current inside the tunneling barrier. Photon detection is then equivalent to a measurement of the current fluctuations at optical frequencies, allowing to probe the tunneling time. Based on this idea, we perform optical spectroscopy and electronic current fluctuation measurements in the far from equilibrium regime. Our experimental data are in very good agreement with theoretical predictions based on the Landauer Büttiker scattering formalism. By combining the optics and the electronics, we directly estimate the so-called traversal time.
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Affiliation(s)
- Pierre Février
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405, Orsay, France
| | - Julien Gabelli
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405, Orsay, France.
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4
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Bülte J, Bednorz A, Bruder C, Belzig W. Noninvasive Quantum Measurement of Arbitrary Operator Order by Engineered Non-Markovian Detectors. PHYSICAL REVIEW LETTERS 2018; 120:140407. [PMID: 29694141 DOI: 10.1103/physrevlett.120.140407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/30/2017] [Indexed: 06/08/2023]
Abstract
The development of solid-state quantum technologies requires the understanding of quantum measurements in interacting, nonisolated quantum systems. In general, a permanent coupling of detectors to a quantum system leads to memory effects that have to be taken into account in interpreting the measurement results. We analyze a generic setup of two detectors coupled to a quantum system and derive a compact formula in the weak-measurement limit that interpolates between an instantaneous (text-book type) and almost continuous-detector dynamics-dependent-measurement. A quantum memory effect that we term "system-mediated detector-detector interaction" is crucial to observe noncommuting observables simultaneously. Finally, we propose a mesoscopic double-dot detector setup in which the memory effect is tunable and that can be used to explore the transition to non-Markovian quantum measurements experimentally.
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Affiliation(s)
- Johannes Bülte
- Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany
| | - Adam Bednorz
- Faculty of Physics, University of Warsaw, Pasteura 5, PL02-093 Warsaw, Poland
| | - Christoph Bruder
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Wolfgang Belzig
- Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany
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5
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Moca CP, Mora C, Weymann I, Zaránd G. Noise of a Chargeless Fermi Liquid. PHYSICAL REVIEW LETTERS 2018; 120:016803. [PMID: 29350969 DOI: 10.1103/physrevlett.120.016803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 10/17/2017] [Indexed: 06/07/2023]
Abstract
We construct a Fermi liquid theory to describe transport in a superconductor-quantum dot-normal metal junction close to the singlet-doublet (parity changing) transition of the dot. Though quasiparticles do not have a definite charge in this chargeless Fermi liquid, in the case of particle-hole symmetry, a mapping to the Anderson model unveils a hidden U(1) symmetry and a corresponding pseudocharge. In contrast to other correlated Fermi liquids, the back scattering noise reveals an effective charge equal to the charge of Cooper pairs, e^{*}=2e. In addition, we find a strong suppression of noise when the linear conductance is unitary, even for its nonlinear part.
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Affiliation(s)
- Cătălin Paşcu Moca
- BME-MTA Exotic Quantum Phase Group, Institute of Physics, Budapest University of Technology and Economics, H-1521 Budapest, Hungary
- Department of Physics, University of Oradea, 410087 Oradea, Romania
| | - Christophe Mora
- Laboratoire Pierre Aigrain, École Normale Supérieure, Université Paris 7 Diderot, CNRS, 24 rue Lhomond, 75005 Paris, France
| | - Ireneusz Weymann
- Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland
| | - Gergely Zaránd
- BME-MTA Exotic Quantum Phase Group, Institute of Physics, Budapest University of Technology and Economics, H-1521 Budapest, Hungary
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6
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Grimsmo AL, Qassemi F, Reulet B, Blais A. Quantum Optics Theory of Electronic Noise in Coherent Conductors. PHYSICAL REVIEW LETTERS 2016; 116:043602. [PMID: 26871330 DOI: 10.1103/physrevlett.116.043602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Indexed: 06/05/2023]
Abstract
We consider the electromagnetic field generated by a coherent conductor in which electron transport is described quantum mechanically. We obtain an input-output relation linking the quantum current in the conductor to the measured electromagnetic field. This allows us to compute the outcome of measurements on the field in terms of the statistical properties of the current. We moreover show how under ac bias the conductor acts as a tunable medium for the field, allowing for the generation of single- and two-mode squeezing through fermionic reservoir engineering. These results explain the recently observed squeezing using normal tunnel junctions [G. Gasse et al., Phys. Rev. Lett. 111, 136601 (2013); J.-C. Forgues et al., Phys. Rev. Lett. 114, 130403 (2015)].
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Affiliation(s)
- Arne L Grimsmo
- Départment de Physique, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec J1K 2R1, Canada
| | - Farzad Qassemi
- Départment de Physique, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec J1K 2R1, Canada
| | - Bertrand Reulet
- Départment de Physique, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec J1K 2R1, Canada
| | - Alexandre Blais
- Départment de Physique, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec J1K 2R1, Canada
- Canadian Institute for Advanced Research, Toronto, Canada
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7
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Jin J, Wang S, Zheng X, Yan Y. Current noise spectra and mechanisms with dissipaton equation of motion theory. J Chem Phys 2015; 142:234108. [DOI: 10.1063/1.4922712] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jinshuang Jin
- Department of Physics, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
| | - Shikuan Wang
- Department of Physics, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Xiao Zheng
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - YiJing Yan
- Hefei National Laboratory for Physical Sciences at the Microscale and iChEM, University of Science and Technology of China, Hefei, Anhui 230026, China
- Department of Chemistry, Hong Kong University of Science and Technology, Hong Kong, China
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8
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Forgues JC, Lupien C, Reulet B. Experimental violation of bell-like inequalities by electronic shot noise. PHYSICAL REVIEW LETTERS 2015; 114:130403. [PMID: 25884119 DOI: 10.1103/physrevlett.114.130403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Indexed: 06/04/2023]
Abstract
We report measurements of the correlations between electromagnetic field quadratures at two frequencies f1=7 GHz and f1=7.5 GHz of the radiation emitted by a tunnel junction placed at very low temperature and excited at frequency f1+f2. We demonstrate the existence of two-mode squeezing and violation of a Bell-like inequality, thereby proving the existence of entanglement in the quantum shot noise radiated by the tunnel junction.
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Affiliation(s)
- Jean-Charles Forgues
- Département de Physique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Christian Lupien
- Département de Physique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Bertrand Reulet
- Département de Physique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
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9
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Parlavecchio O, Altimiras C, Souquet JR, Simon P, Safi I, Joyez P, Vion D, Roche P, Esteve D, Portier F. Fluctuation-dissipation relations of a tunnel junction driven by a quantum circuit. PHYSICAL REVIEW LETTERS 2015; 114:126801. [PMID: 25860764 DOI: 10.1103/physrevlett.114.126801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Indexed: 06/04/2023]
Abstract
We derive fluctuation-dissipation relations for a tunnel junction driven through a resonator displaying strong quantum fluctuations. We find that the fluctuation-dissipation relations derived for classical external drives hold, provided the effect of the circuit's quantum fluctuations is incorporated into the modified nonlinear current voltage characteristics. We also demonstrate that all quantities measured under a time dependent bias can be reconstructed from their values measured under a dc bias using photoassisted tunneling relations. We confirm these predictions by implementing the circuit and measuring the dc current through the junction, its high frequency admittance, and its current noise at the frequency of the resonator.
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Affiliation(s)
- O Parlavecchio
- SPEC (UMR 3680 CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - C Altimiras
- SPEC (UMR 3680 CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - J-R Souquet
- Laboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay, France
| | - P Simon
- Laboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay, France
| | - I Safi
- Laboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay, France
| | - P Joyez
- SPEC (UMR 3680 CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - D Vion
- SPEC (UMR 3680 CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - P Roche
- SPEC (UMR 3680 CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - D Esteve
- SPEC (UMR 3680 CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - F Portier
- SPEC (UMR 3680 CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette, France
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10
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Souquet JR, Woolley MJ, Gabelli J, Simon P, Clerk AA. Photon-assisted tunnelling with nonclassical light. Nat Commun 2014; 5:5562. [PMID: 25424422 PMCID: PMC4263132 DOI: 10.1038/ncomms6562] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Accepted: 10/14/2014] [Indexed: 11/23/2022] Open
Abstract
Among the most exciting recent advances in the field of superconducting quantum circuits is the ability to coherently couple microwave photons in low-loss cavities to quantum electronic conductors. These hybrid quantum systems hold great promise for quantum information-processing applications; even more strikingly, they enable exploration of new physical regimes. Here we study theoretically the new physics emerging when a quantum electronic conductor is exposed to nonclassical microwaves (for example, squeezed states, Fock states). We study this interplay in the experimentally relevant situation where a superconducting microwave cavity is coupled to a conductor in the tunnelling regime. We find that the conductor acts as a nontrivial probe of the microwave state: the emission and absorption of photons by the conductor is characterized by a nonpositive definite quasi-probability distribution, which is related to the Glauber–Sudarshan P-function of quantum optics. These negative quasi-probabilities have a direct influence on the conductance of the conductor. Coherently coupling microwave photons to quantum electronic conductors could provide a useful platform for quantum information processing. Souquet et al. now theoretically demonstrate that such systems can also act as sensitive probes of the quantum properties of non-classical microwave radiation.
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Affiliation(s)
- J-R Souquet
- 1] Laboratoire de Physique des Solides, Université Paris-Sud, Orsay 91405, France [2] Department of Physics, McGill University, Montréal, Quebec, Canada
| | - M J Woolley
- School of Engineering and Information Technology, University of New South Wales, ADFA, Canberra, Australian Capital Territory 2600, Australia
| | - J Gabelli
- Laboratoire de Physique des Solides, Université Paris-Sud, Orsay 91405, France
| | - P Simon
- Laboratoire de Physique des Solides, Université Paris-Sud, Orsay 91405, France
| | - A A Clerk
- Department of Physics, McGill University, Montréal, Quebec, Canada
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11
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Forgues JC, Lupien C, Reulet B. Emission of microwave photon pairs by a tunnel junction. PHYSICAL REVIEW LETTERS 2014; 113:043602. [PMID: 25105619 DOI: 10.1103/physrevlett.113.043602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Indexed: 06/03/2023]
Abstract
We report the observation of photon pairs in the photoassisted shot noise of a tunnel junction in the quantum regime at very high frequency and very low temperature. We have measured the fluctuations of the noise power generated by the junction at two different frequencies, f(1) = 4.4 and f(2) = 7.2 GHz, while driving the junction with a microwave excitation of frequency f(0) = f(1) + f(2). We observe clear correlations between the fluctuations of the two noise powers even when the mean photon number per measurement is much smaller than one. This is strong evidence for photons being emitted in pairs. We also demonstrate that the electromagnetic field generated by the junction exhibits two-mode amplitude squeezing, a proof of its nonclassicality. The data agree very well with predictions based on the fourth cumulant of the current fluctuations generated by the junction.
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Affiliation(s)
- Jean-Charles Forgues
- Département de Physique, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1
| | - Christian Lupien
- Département de Physique, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1
| | - Bertrand Reulet
- Département de Physique, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1
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12
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Noise intensity-intensity correlations and the fourth cumulant of photo-assisted shot noise. Sci Rep 2013; 3:2869. [PMID: 24100407 PMCID: PMC3792424 DOI: 10.1038/srep02869] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 09/19/2013] [Indexed: 11/24/2022] Open
Abstract
We report the measurement of the fourth cumulant of current fluctuations in a tunnel junction under both dc and ac (microwave) excitation. This probes the non-Gaussian character of photo-assisted shot noise. Our measurement reveals the existence of correlations between noise power measured at two different frequencies, which corresponds to two-mode intensity correlations in optics. We observe positive correlations, i.e. photon bunching, which exist only for certain relations between the excitation frequency and the two detection frequencies, depending on the dc bias of the sample.
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13
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Gasse G, Lupien C, Reulet B. Observation of squeezing in the electron quantum shot noise of a tunnel junction. PHYSICAL REVIEW LETTERS 2013; 111:136601. [PMID: 24116798 DOI: 10.1103/physrevlett.111.136601] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Indexed: 06/02/2023]
Abstract
We report the measurement of the fluctuations of the two quadratures of the electromagnetic field generated by a quantum conductor, a dc- and ac-biased tunnel junction placed at very low temperature. We observe that the variance of the fluctuations on one quadrature can go below that of vacuum, i.e., that the radiated field is squeezed. This demonstrates the quantum nature of the radiated electromagnetic field.
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Affiliation(s)
- Gabriel Gasse
- Département de Physique, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1
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14
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Bednorz A, Bruder C, Reulet B, Belzig W. Nonsymmetrized correlations in quantum noninvasive measurements. PHYSICAL REVIEW LETTERS 2013; 110:250404. [PMID: 23829718 DOI: 10.1103/physrevlett.110.250404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Indexed: 06/02/2023]
Abstract
A long-standing problem in quantum mesoscopic physics is which operator order corresponds to noise expressions like <I(-ω)I(ω)>, where I(ω) is the measured current at frequency ω. Symmetrized order describes a classical measurement while nonsymmetrized order corresponds to a quantum detector, e.g., one sensitive to either emission or absorption of photons. We show that both order schemes can be embedded in quantum weak-measurement theory taking into account measurements with memory, characterized by a memory function which is independent of a particular experimental detection scheme. We discuss the resulting quasiprobabilities for different detector temperatures and how their negativity can be tested on the level of second-order correlation functions already. Experimentally, this negativity can be related to the squeezing of the many-body state of the transported electrons in an ac-driven tunnel junction.
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Affiliation(s)
- Adam Bednorz
- Faculty of Physics, University of Warsaw, ul. Hoża 69, PL00-681 Warsaw, Poland.
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15
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Filippone M, Le Hur K, Mora C. Giant charge relaxation resistance in the Anderson model. PHYSICAL REVIEW LETTERS 2011; 107:176601. [PMID: 22107549 DOI: 10.1103/physrevlett.107.176601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Indexed: 05/31/2023]
Abstract
We investigate the dynamical charge response of the Anderson model viewed as a quantum RC circuit. Applying a low-energy effective Fermi liquid theory, a generalized Korringa-Shiba formula is derived at zero temperature, and the charge relaxation resistance is expressed solely in terms of static susceptibilities which are accessible by Bethe ansatz. We identify a giant charge relaxation resistance at intermediate magnetic fields related to the destruction of the Kondo singlet. The scaling properties of this peak are computed analytically in the Kondo regime. We also show that the resistance peak fades away at the particle-hole symmetric point.
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Affiliation(s)
- Michele Filippone
- Laboratoire Pierre Aigrain, École Normale Supérieure, Université Paris 7 Diderot, CNRS, 24 rue Lhomond, 75005 Paris, France
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16
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Basset J, Bouchiat H, Deblock R. Emission and absorption quantum noise measurement with an on-chip resonant circuit. PHYSICAL REVIEW LETTERS 2010; 105:166801. [PMID: 21230992 DOI: 10.1103/physrevlett.105.166801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Indexed: 05/30/2023]
Abstract
Using a quantum detector, a superconductor-insulator-superconductor junction, we probe separately the emission and absorption noise in the quantum regime of a superconducting resonant circuit at equilibrium. At low temperature the resonant circuit exhibits only absorption noise related to zero point fluctuations, whereas at higher temperature emission noise is also present. By coupling a Josephson junction, biased above the superconducting gap, to the same resonant circuit, we directly measure the noise power of quasiparticles tunneling through the junction at two resonance frequencies. It exhibits a strong frequency dependence, consistent with theoretical predictions.
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Affiliation(s)
- J Basset
- Laboratoire de Physique des Solides, Université Paris-Sud, CNRS, UMR 8502, F-91405 Orsay Cedex, France
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17
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Bednorz A, Belzig W. Quasiprobabilistic interpretation of weak measurements in mesoscopic junctions. PHYSICAL REVIEW LETTERS 2010; 105:106803. [PMID: 20867538 DOI: 10.1103/physrevlett.105.106803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Indexed: 05/29/2023]
Abstract
The impossibility of measuring noncommuting quantum mechanical observables is one of the most fascinating consequences of the quantum mechanical postulates. Hence, to date the investigation of quantum measurement and projection is a fundamentally interesting topic. We propose to test the concept of weak measurement of noncommuting observables in mesoscopic transport experiments, using a quasiprobabilistic description. We derive an inequality for current correlators, which is satisfied by every classical probability but violated by high-frequency fourth-order cumulants in the quantum regime for experimentally feasible parameters.
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Affiliation(s)
- Adam Bednorz
- Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany.
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18
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Menzel EP, Deppe F, Mariantoni M, Araque Caballero MA, Baust A, Niemczyk T, Hoffmann E, Marx A, Solano E, Gross R. Dual-path state reconstruction scheme for propagating quantum microwaves and detector noise tomography. PHYSICAL REVIEW LETTERS 2010; 105:100401. [PMID: 20867495 DOI: 10.1103/physrevlett.105.100401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 07/21/2010] [Indexed: 05/29/2023]
Abstract
Quantum state reconstruction of weak propagating microwaves to date requires the use of linear amplifiers. We introduce a theory which, even in the presence of significant amplifier noise, allows one to use these devices for measuring all quadrature moments of propagating quantum microwaves based on cross correlations from a dual-path amplification setup. Simultaneously, the detector noise properties are determined, allowing for tomography. We demonstrate the feasibility of our novel concept by proof-of-principle experiments with classical mixtures of weak coherent microwaves.
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Affiliation(s)
- E P Menzel
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany.
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19
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Bednorz A, Belzig W. Formulation of time-resolved counting statistics based on a positive-operator-valued measure. PHYSICAL REVIEW LETTERS 2008; 101:206803. [PMID: 19113367 DOI: 10.1103/physrevlett.101.206803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Indexed: 05/27/2023]
Abstract
We propose a derivation of the full counting statistics of electronic current based on a positive-operator-valued measure. Our approach justifies the Levitov-Lesovik formula in the long-time limit, but can be generalized to the detection of finite-frequency noise correlations. The combined action of the projection postulate and the quantum formula for current noise at high frequencies imply an additional white noise. Estimates for this additional noise are in accordance with known experiments. We propose an experimental test of our conjecture by a simultaneous measurement of high- and low-frequency noise.
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Affiliation(s)
- Adam Bednorz
- Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany and University of Warsaw, Hoza 69, PL-00681 Warsaw, Poland.
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20
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Förster H, Büttiker M. Fluctuation relations without microreversibility in nonlinear transport. PHYSICAL REVIEW LETTERS 2008; 101:136805. [PMID: 18851481 DOI: 10.1103/physrevlett.101.136805] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Indexed: 05/26/2023]
Abstract
In linear transport, the fluctuation-dissipation theorem relates equilibrium current correlations to the linear conductance coefficient. For nonlinear transport, there exist fluctuation relations that rely on Onsager's principle of microscopic reversibility away from equilibrium. However, both theory and experiments have shown deviations from microreversibility in the form of magnetic field asymmetric current-voltage relations. We present novel fluctuation relations for nonlinear transport in the presence of magnetic fields that relate current correlation functions at any order at equilibrium to response coefficients of current cumulants of lower order. We illustrate our results with the example of an electrical Mach-Zehnder interferometer.
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Affiliation(s)
- H Förster
- Département de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland
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Park HC, Ahn KH. Admittance and noise in an electrically driven nanostructure: interplay between quantum coherence and statistics. PHYSICAL REVIEW LETTERS 2008; 101:116804. [PMID: 18851311 DOI: 10.1103/physrevlett.101.116804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Indexed: 05/26/2023]
Abstract
We investigate the interplay between the quantum coherence and statistics in electrically driven nanostructures. We obtain an expression for the admittance and the current noise for a driven nanocapacitor in terms of the Floquet scattering matrix and derive a nonequilibrium fluctuation-dissipation relation. As an interplay between the quantum phase coherence and the many-body correlation, the admittance has peak values whenever the noise power shows a step as a function of the nearby gate voltage. Our theory is demonstrated by calculating the admittance and noise of driven double-quantum dots.
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Affiliation(s)
- Hee Chul Park
- Department of Physics, Chungnam National University, Daejeon 305-764, Republic of Korea
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