1
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D'Arrigo A, Piccitto G, Falci G, Paladino E. Open-loop quantum control of small-size networks for high-order cumulants and cross-correlations sensing. Sci Rep 2024; 14:16681. [PMID: 39030340 PMCID: PMC11271536 DOI: 10.1038/s41598-024-67503-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 07/11/2024] [Indexed: 07/21/2024] Open
Abstract
Quantum control techniques are one of the most efficient tools for attaining high-fidelity quantum operations and a convenient approach for quantum sensing and quantum noise spectroscopy. In this work, we investigate dynamical decoupling while processing an entangling two-qubit gate based on an Ising-xx interaction, each qubit affected by pure dephasing classical correlated 1/f-noises. To evaluate the gate error, we used the Magnus expansion introducing generalized filter functions that describe decoupling while processing and allow us to derive an approximate analytic expression as a hierarchy of nested integrals of noise cumulants. The error is separated in contributions of Gaussian and non-Gaussian noise, with the corresponding generalized filter functions calculated up to the fourth order. By exploiting the properties of selected pulse sequences, we show that it is possible to extract the second-order statistics (spectrum and cross-spectrum) and to highlight non-Gaussian features contained in the fourth-order cumulant. We discuss the applicability of these results to state-of-the-art small networks based on solid-state platforms.
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Affiliation(s)
- Antonio D'Arrigo
- Dipartimento di Fisica e Astronomia "Ettore Majorana", Università di Catania, Via Santa Sofia 64, 95123, Catania, Italy
| | - Giulia Piccitto
- Dipartimento di Matematica e Informatica, Università di Catania, Viale Andrea Doria, 95125, Catania, Italy
| | - Giuseppe Falci
- Dipartimento di Fisica e Astronomia "Ettore Majorana", Università di Catania, Via Santa Sofia 64, 95123, Catania, Italy
- CNR-IMM, Catania (University unit), Consiglio Nazionale delle Ricerche, Via Santa Sofia 64, 95123, Catania, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Via Santa Sofia 64, 95123, Catania, Italy
| | - Elisabetta Paladino
- Dipartimento di Fisica e Astronomia "Ettore Majorana", Università di Catania, Via Santa Sofia 64, 95123, Catania, Italy.
- CNR-IMM, Catania (University unit), Consiglio Nazionale delle Ricerche, Via Santa Sofia 64, 95123, Catania, Italy.
- Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Via Santa Sofia 64, 95123, Catania, Italy.
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2
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Zou J, Bosco S, Loss D. Spatially correlated classical and quantum noise in driven qubits. NPJ QUANTUM INFORMATION 2024; 10:46. [PMID: 38706554 PMCID: PMC11062932 DOI: 10.1038/s41534-024-00842-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 04/17/2024] [Indexed: 05/07/2024]
Abstract
Correlated noise across multiple qubits poses a significant challenge for achieving scalable and fault-tolerant quantum processors. Despite recent experimental efforts to quantify this noise in various qubit architectures, a comprehensive understanding of its role in qubit dynamics remains elusive. Here, we present an analytical study of the dynamics of driven qubits under spatially correlated noise, including both Markovian and non-Markovian noise. Surprisingly, we find that by operating the qubit system at low temperatures, where correlated quantum noise plays an important role, significant long-lived entanglement between qubits can be generated. Importantly, this generation process can be controlled on-demand by turning the qubit driving on and off. On the other hand, we demonstrate that by operating the system at a higher temperature, the crosstalk between qubits induced by the correlated noise is unexpectedly suppressed. We finally reveal the impact of spatio-temporally correlated 1/f noise on the decoherence rate, and how its temporal correlations restore lost entanglement. Our findings provide critical insights into not only suppressing crosstalk between qubits caused by correlated noise but also in effectively leveraging such noise as a beneficial resource for controlled entanglement generation.
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Affiliation(s)
- Ji Zou
- Department of Physics, University of Basel, Basel, Switzerland
| | - Stefano Bosco
- Department of Physics, University of Basel, Basel, Switzerland
| | - Daniel Loss
- Department of Physics, University of Basel, Basel, Switzerland
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3
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Teoh JD, Winkel P, Babla HK, Chapman BJ, Claes J, de Graaf SJ, Garmon JWO, Kalfus WD, Lu Y, Maiti A, Sahay K, Thakur N, Tsunoda T, Xue SH, Frunzio L, Girvin SM, Puri S, Schoelkopf RJ. Dual-rail encoding with superconducting cavities. Proc Natl Acad Sci U S A 2023; 120:e2221736120. [PMID: 37801473 PMCID: PMC10576063 DOI: 10.1073/pnas.2221736120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 08/07/2023] [Indexed: 10/08/2023] Open
Abstract
The design of quantum hardware that reduces and mitigates errors is essential for practical quantum error correction (QEC) and useful quantum computation. To this end, we introduce the circuit-Quantum Electrodynamics (QED) dual-rail qubit in which our physical qubit is encoded in the single-photon subspace, [Formula: see text], of two superconducting microwave cavities. The dominant photon loss errors can be detected and converted into erasure errors, which are in general much easier to correct. In contrast to linear optics, a circuit-QED implementation of the dual-rail code offers unique capabilities. Using just one additional transmon ancilla per dual-rail qubit, we describe how to perform a gate-based set of universal operations that includes state preparation, logical readout, and parametrizable single and two-qubit gates. Moreover, first-order hardware errors in the cavities and the transmon can be detected and converted to erasure errors in all operations, leaving background Pauli errors that are orders of magnitude smaller. Hence, the dual-rail cavity qubit exhibits a favorable hierarchy of error rates and is expected to perform well below the relevant QEC thresholds with today's coherence times.
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Affiliation(s)
- James D. Teoh
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Patrick Winkel
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Harshvardhan K. Babla
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Benjamin J. Chapman
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Jahan Claes
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Stijn J. de Graaf
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - John W. O. Garmon
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - William D. Kalfus
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Yao Lu
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Aniket Maiti
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Kaavya Sahay
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Neel Thakur
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Takahiro Tsunoda
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Sophia H. Xue
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Luigi Frunzio
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Steven M. Girvin
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Shruti Puri
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Robert J. Schoelkopf
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
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4
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Rower DA, Ateshian L, Li LH, Hays M, Bluvstein D, Ding L, Kannan B, Almanakly A, Braumüller J, Kim DK, Melville A, Niedzielski BM, Schwartz ME, Yoder JL, Orlando TP, Wang JIJ, Gustavsson S, Grover JA, Serniak K, Comin R, Oliver WD. Evolution of 1/f Flux Noise in Superconducting Qubits with Weak Magnetic Fields. PHYSICAL REVIEW LETTERS 2023; 130:220602. [PMID: 37327421 DOI: 10.1103/physrevlett.130.220602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 04/12/2023] [Indexed: 06/18/2023]
Abstract
The microscopic description of 1/f magnetic flux noise in superconducting circuits has remained an open question for several decades despite extensive experimental and theoretical investigation. Recent progress in superconducting devices for quantum information has highlighted the need to mitigate sources of qubit decoherence, driving a renewed interest in understanding the underlying noise mechanism(s). Though a consensus has emerged attributing flux noise to surface spins, their identity and interaction mechanisms remain unclear, prompting further study. Here, we apply weak in-plane magnetic fields to a capacitively shunted flux qubit (where the Zeeman splitting of surface spins lies below the device temperature) and study the flux-noise-limited qubit dephasing, revealing previously unexplored trends that may shed light on the dynamics behind the emergent 1/f noise. Notably, we observe an enhancement (suppression) of the spin-echo (Ramsey) pure-dephasing time in fields up to B=100 G. With direct noise spectroscopy, we further observe a transition from a 1/f to approximately Lorentzian frequency dependence below 10 Hz and a reduction of the noise above 1 MHz with increasing magnetic field. We suggest that these trends are qualitatively consistent with an increase of spin cluster sizes with magnetic field. These results should help to inform a complete microscopic theory of 1/f flux noise in superconducting circuits.
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Affiliation(s)
- David A Rower
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Lamia Ateshian
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Lauren H Li
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Max Hays
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Dolev Bluvstein
- Department of Physics, Harvard University, Cambridge, Massachusetts 02139, USA
| | - Leon Ding
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Bharath Kannan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Aziza Almanakly
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jochen Braumüller
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - David K Kim
- MIT Lincoln Laboratory, Lexington, Massachusetts 02421, USA
| | | | | | | | | | - Terry P Orlando
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Joel I-Jan Wang
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jeffrey A Grover
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Kyle Serniak
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT Lincoln Laboratory, Lexington, Massachusetts 02421, USA
| | - Riccardo Comin
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - William D Oliver
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT Lincoln Laboratory, Lexington, Massachusetts 02421, USA
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5
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Montenegro V, Jones GS, Bose S, Bayat A. Sequential Measurements for Quantum-Enhanced Magnetometry in Spin Chain Probes. PHYSICAL REVIEW LETTERS 2022; 129:120503. [PMID: 36179207 DOI: 10.1103/physrevlett.129.120503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 08/23/2022] [Indexed: 06/16/2023]
Abstract
Quantum sensors outperform their classical counterparts in their estimation precision, given the same amount of resources. So far, quantum-enhanced sensitivity has been achieved by exploiting the superposition principle. This enhancement has been obtained for particular forms of entangled states, adaptive measurement basis change, critical many-body systems, and steady state of periodically driven systems. Here, we introduce a different approach to obtain quantum-enhanced sensitivity in a many-body probe through utilizing the nature of quantum measurement and its subsequent wave function collapse without demanding prior entanglement. Our protocol consists of a sequence of local measurements, without reinitialization, performed regularly during the evolution of a many-body probe. As the number of sequences increases, the sensing precision is enhanced beyond the standard limit, reaching the Heisenberg bound asymptotically. The benefits of the protocol are multifold as it uses a product initial state and avoids complex initialization (e.g., prior entangled states or critical ground states) and allows for remote quantum sensing.
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Affiliation(s)
- Victor Montenegro
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610051, China
| | - Gareth Siôn Jones
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Sougato Bose
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Abolfazl Bayat
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610051, China
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6
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Quantum nonlinear spectroscopy of single nuclear spins. Nat Commun 2022; 13:5318. [PMID: 36085280 PMCID: PMC9463177 DOI: 10.1038/s41467-022-32610-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 08/04/2022] [Indexed: 11/30/2022] Open
Abstract
Conventional nonlinear spectroscopy, which use classical probes, can only access a limited set of correlations in a quantum system. Here we demonstrate that quantum nonlinear spectroscopy, in which a quantum sensor and a quantum object are first entangled and the sensor is measured along a chosen basis, can extract arbitrary types and orders of correlations in a quantum system. We measured fourth-order correlations of single nuclear spins that cannot be measured in conventional nonlinear spectroscopy, using sequential weak measurement via a nitrogen-vacancy center in diamond. The quantum nonlinear spectroscopy provides fingerprint features to identify different types of objects, such as Gaussian noises, random-phased AC fields, and quantum spins, which would be indistinguishable in second-order correlations. This work constitutes an initial step toward the application of higher-order correlations to quantum sensing, to examining the quantum foundation (by, e.g., higher-order Leggett-Garg inequality), and to studying quantum many-body physics. Signals that look the same from their low-order correlations can often be distinguished by looking at higher-order ones. Here, the authors exploit the sensitivity of quantum nonlinear spectroscopy to fourth-order correlations to identify Gaussian noises, random-phased AC fields, and quantum spins.
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7
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Wang G, Liu YX, Zhu Y, Cappellaro P. Nanoscale Vector AC Magnetometry with a Single Nitrogen-Vacancy Center in Diamond. NANO LETTERS 2021; 21:5143-5150. [PMID: 34086471 DOI: 10.1021/acs.nanolett.1c01165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Detection of AC magnetic fields at the nanoscale is critical in applications ranging from fundamental physics to materials science. Isolated quantum spin defects, such as the nitrogen-vacancy center in diamond, can achieve the desired spatial resolution with high sensitivity. Still, vector AC magnetometry currently relies on using different orientations of an ensemble of sensors, with degraded spatial resolution, and a protocol based on a single NV is lacking. Here we propose and experimentally demonstrate a protocol that exploits a single NV to reconstruct the vectorial components of an AC magnetic field by tuning a continuous driving to distinct resonance conditions. We map the spatial distribution of an AC field generated by a copper wire on the surface of the diamond. The proposed protocol combines high sensitivity, broad dynamic range, and sensitivity to both coherent and stochastic signals, with broad applications in condensed matter physics, such as probing spin fluctuations.
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Affiliation(s)
- Guoqing Wang
- Research Laboratory of Electronics and Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yi-Xiang Liu
- Research Laboratory of Electronics and Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Yuan Zhu
- Research Laboratory of Electronics and Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Paola Cappellaro
- Research Laboratory of Electronics and Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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8
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Multiscale Thermodynamics: Energy, Entropy, and Symmetry from Atoms to Bulk Behavior. Symmetry (Basel) 2021. [DOI: 10.3390/sym13040721] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Here, we investigate how the local properties of particles in a thermal bath may influence the thermodynamics of the bath, and consequently alter the statistical mechanics of subsystems that comprise the bath. We are guided by the theory of small-system thermodynamics, which is based on two primary postulates: that small systems can be treated self-consistently by coupling them to an ensemble of similarly small systems, and that a large ensemble of small systems forms its own thermodynamic bath. We adapt this “nanothermodynamics” to investigate how a large system may subdivide into an ensemble of smaller subsystems, causing internal heterogeneity across multiple size scales. For the semi-classical ideal gas, maximum entropy favors subdividing a large system of “atoms” into an ensemble of “regions” of variable size. The mechanism of region formation could come from quantum exchange symmetry that makes atoms in each region indistinguishable, while decoherence between regions allows atoms in separate regions to be distinguishable by their distinct locations. Combining regions reduces the total entropy, as expected when distinguishable particles become indistinguishable, and as required by a theorem in quantum mechanics for sub-additive entropy. Combining large volumes of small regions gives the usual entropy of mixing for a semi-classical ideal gas, resolving Gibbs paradox without invoking quantum symmetry for particles that may be meters apart. Other models presented here are based on Ising-like spins, which are solved analytically in one dimension. Focusing on the bonds between the spins, we find similarity in the equilibrium properties of a two-state model in the nanocanonical ensemble and a three-state model in the canonical ensemble. Thus, emergent phenomena may alter the thermal behavior of microscopic models, and the correct ensemble is necessary for fully-accurate predictions. Another result using Ising-like spins involves simulations that include a nonlinear correction to Boltzmann’s factor, which mimics the statistics of indistinguishable states by imitating the dynamics of spin exchange on intermediate lengths. These simulations exhibit 1/f-like noise at low frequencies (f), and white noise at higher f, similar to the equilibrium thermal fluctuations found in many materials.
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9
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Sung Y, Vepsäläinen A, Braumüller J, Yan F, Wang JIJ, Kjaergaard M, Winik R, Krantz P, Bengtsson A, Melville AJ, Niedzielski BM, Schwartz ME, Kim DK, Yoder JL, Orlando TP, Gustavsson S, Oliver WD. Multi-level quantum noise spectroscopy. Nat Commun 2021; 12:967. [PMID: 33574240 PMCID: PMC7878521 DOI: 10.1038/s41467-021-21098-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 01/13/2021] [Indexed: 11/08/2022] Open
Abstract
System noise identification is crucial to the engineering of robust quantum systems. Although existing quantum noise spectroscopy (QNS) protocols measure an aggregate amount of noise affecting a quantum system, they generally cannot distinguish between the underlying processes that contribute to it. Here, we propose and experimentally validate a spin-locking-based QNS protocol that exploits the multi-level energy structure of a superconducting qubit to achieve two notable advances. First, our protocol extends the spectral range of weakly anharmonic qubit spectrometers beyond the present limitations set by their lack of strong anharmonicity. Second, the additional information gained from probing the higher-excited levels enables us to identify and distinguish contributions from different underlying noise mechanisms.
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Affiliation(s)
- Youngkyu Sung
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Antti Vepsäläinen
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jochen Braumüller
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Fei Yan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Joel I-Jan Wang
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Morten Kjaergaard
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Roni Winik
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Philip Krantz
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Andreas Bengtsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | | | | | | | - Terry P Orlando
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - William D Oliver
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
- MIT Lincoln Laboratory, Lexington, MA, USA.
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
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10
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Szombati D, Gomez Frieiro A, Müller C, Jones T, Jerger M, Fedorov A. Quantum Rifling: Protecting a Qubit from Measurement Back Action. PHYSICAL REVIEW LETTERS 2020; 124:070401. [PMID: 32142306 DOI: 10.1103/physrevlett.124.070401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 01/27/2020] [Indexed: 06/10/2023]
Abstract
Quantum mechanics postulates that measuring the qubit's wave function results in its collapse, with the recorded discrete outcome designating the particular eigenstate that the qubit collapsed into. We show that this picture breaks down when the qubit is strongly driven during measurement. More specifically, for a fast evolving qubit the measurement returns the time-averaged expectation value of the measurement operator, erasing information about the initial state of the qubit while completely suppressing the measurement backaction. We call this regime quantum rifling, as the fast spinning of the Bloch vector protects it from deflection into either of its eigenstates. We study this phenomenon with two superconducting qubits coupled to the same probe field and demonstrate that quantum rifling allows us to measure either one of the qubits on demand while protecting the state of the other from measurement backaction. Our results allow for the implementation of selective readout multiplexing of several qubits, contributing to the efficient scaling up of quantum processors for future quantum technologies.
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Affiliation(s)
- Daniel Szombati
- ARC Centre of Excellence for Engineered Quantum Systems, St Lucia, Queensland 4072, Australia
- School of Mathematics and Physics, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Alejandro Gomez Frieiro
- ARC Centre of Excellence for Engineered Quantum Systems, St Lucia, Queensland 4072, Australia
- School of Mathematics and Physics, University of Queensland, St Lucia, Queensland 4072, Australia
| | | | - Tyler Jones
- ARC Centre of Excellence for Engineered Quantum Systems, St Lucia, Queensland 4072, Australia
- School of Mathematics and Physics, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Markus Jerger
- ARC Centre of Excellence for Engineered Quantum Systems, St Lucia, Queensland 4072, Australia
- School of Mathematics and Physics, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Arkady Fedorov
- ARC Centre of Excellence for Engineered Quantum Systems, St Lucia, Queensland 4072, Australia
- School of Mathematics and Physics, University of Queensland, St Lucia, Queensland 4072, Australia
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11
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Extension of the Coherence Time by Generating MW Dressed States in a Single NV Centre in Diamond. Sci Rep 2019; 9:13318. [PMID: 31527609 PMCID: PMC6746786 DOI: 10.1038/s41598-019-49683-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/31/2019] [Indexed: 11/09/2022] Open
Abstract
Nitrogen-vacancy (NV) centres in diamond hold promise in quantum sensing applications. A major interest in them is an enhancement of their sensitivity by the extension of the coherence time (T2). In this report, we experimentally generated more than four dressed states in a single NV centre in diamond based on Autler-Townes splitting (ATS). We also observed the extension of the coherence time to T2 ~ 1.5 ms which is more than two orders of magnitude longer than that of the undressed states. As an example of a quantum application using these results we propose a protocol of quantum sensing, which shows more than an order of magnitude enhancement in the sensitivity.
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12
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Sung Y, Beaudoin F, Norris LM, Yan F, Kim DK, Qiu JY, von Lüpke U, Yoder JL, Orlando TP, Gustavsson S, Viola L, Oliver WD. Non-Gaussian noise spectroscopy with a superconducting qubit sensor. Nat Commun 2019; 10:3715. [PMID: 31527608 PMCID: PMC6746758 DOI: 10.1038/s41467-019-11699-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 07/30/2019] [Indexed: 11/17/2022] Open
Abstract
Accurate characterization of the noise influencing a quantum system of interest has far-reaching implications across quantum science, ranging from microscopic modeling of decoherence dynamics to noise-optimized quantum control. While the assumption that noise obeys Gaussian statistics is commonly employed, noise is generically non-Gaussian in nature. In particular, the Gaussian approximation breaks down whenever a qubit is strongly coupled to discrete noise sources or has a non-linear response to the environmental degrees of freedom. Thus, in order to both scrutinize the applicability of the Gaussian assumption and capture distinctive non-Gaussian signatures, a tool for characterizing non-Gaussian noise is essential. Here, we experimentally validate a quantum control protocol which, in addition to the spectrum, reconstructs the leading higher-order spectrum of engineered non-Gaussian dephasing noise using a superconducting qubit as a sensor. This first experimental demonstration of non-Gaussian noise spectroscopy represents a major step toward demonstrating a complete spectral estimation toolbox for quantum devices.
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Affiliation(s)
- Youngkyu Sung
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Félix Beaudoin
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH, 03755, USA
- NanoAcademic Technologies, 666 rue Sherbrooke Ouest, Suite 802, Montreal, Quebec, H3A 1E7, Canada
| | - Leigh M Norris
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH, 03755, USA
| | - Fei Yan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - David K Kim
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, MA, 02421, USA
| | - Jack Y Qiu
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Uwe von Lüpke
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Jonilyn L Yoder
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, MA, 02421, USA
| | - Terry P Orlando
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Lorenza Viola
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH, 03755, USA.
| | - William D Oliver
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, MA, 02421, USA.
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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13
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Yan F, Campbell D, Krantz P, Kjaergaard M, Kim D, Yoder JL, Hover D, Sears A, Kerman AJ, Orlando TP, Gustavsson S, Oliver WD. Distinguishing Coherent and Thermal Photon Noise in a Circuit Quantum Electrodynamical System. PHYSICAL REVIEW LETTERS 2018; 120:260504. [PMID: 30004727 DOI: 10.1103/physrevlett.120.260504] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Indexed: 06/08/2023]
Abstract
In the cavity-QED architecture, photon number fluctuations from residual cavity photons cause qubit dephasing due to the ac Stark effect. These unwanted photons originate from a variety of sources, such as thermal radiation, leftover measurement photons, and cross talk. Using a capacitively shunted flux qubit coupled to a transmission line cavity, we demonstrate a method that identifies and distinguishes coherent and thermal photons based on noise-spectral reconstruction from time-domain spin-locking relaxometry. Using these measurements, we attribute the limiting dephasing source in our system to thermal photons rather than coherent photons. By improving the cryogenic attenuation on lines leading to the cavity, we successfully suppress residual thermal photons and achieve T_{1}-limited spin-echo decay time. The spin-locking noise-spectroscopy technique allows broad frequency access and readily applies to other qubit modalities for identifying general asymmetric nonclassical noise spectra.
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Affiliation(s)
- Fei Yan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Dan Campbell
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Philip Krantz
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Morten Kjaergaard
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - David Kim
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Jonilyn L Yoder
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - David Hover
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Adam Sears
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Andrew J Kerman
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Terry P Orlando
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - William D Oliver
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, Massachusetts 02420, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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14
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Kapit E. Error-Transparent Quantum Gates for Small Logical Qubit Architectures. PHYSICAL REVIEW LETTERS 2018; 120:050503. [PMID: 29481172 DOI: 10.1103/physrevlett.120.050503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Indexed: 06/08/2023]
Abstract
One of the largest obstacles to building a quantum computer is gate error, where the physical evolution of the state of a qubit or group of qubits during a gate operation does not match the intended unitary transformation. Gate error stems from a combination of control errors and random single qubit errors from interaction with the environment. While great strides have been made in mitigating control errors, intrinsic qubit error remains a serious problem that limits gate fidelity in modern qubit architectures. Simultaneously, recent developments of small error-corrected logical qubit devices promise significant increases in logical state lifetime, but translating those improvements into increases in gate fidelity is a complex challenge. In this Letter, we construct protocols for gates on and between small logical qubit devices which inherit the parent device's tolerance to single qubit errors which occur at any time before or during the gate. We consider two such devices, a passive implementation of the three-qubit bit flip code, and the author's own [E. Kapit, Phys. Rev. Lett. 116, 150501 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.150501] very small logical qubit (VSLQ) design, and propose error-tolerant gate sets for both. The effective logical gate error rate in these models displays superlinear error reduction with linear increases in single qubit lifetime, proving that passive error correction is capable of increasing gate fidelity. Using a standard phenomenological noise model for superconducting qubits, we demonstrate a realistic, universal one- and two-qubit gate set for the VSLQ, with error rates an order of magnitude lower than those for same-duration operations on single qubits or pairs of qubits. These developments further suggest that incorporating small logical qubits into a measurement based code could substantially improve code performance.
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Affiliation(s)
- Eliot Kapit
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
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15
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Szańkowski P, Ramon G, Krzywda J, Kwiatkowski D, Cywiński Ł. Environmental noise spectroscopy with qubits subjected to dynamical decoupling. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:333001. [PMID: 28569239 DOI: 10.1088/1361-648x/aa7648] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A qubit subjected to pure dephasing due to classical Gaussian noise can be turned into a spectrometer of this noise by utilizing its readout under properly chosen dynamical decoupling (DD) sequences to reconstruct the power spectral density of the noise. We review the theory behind this DD-based noise spectroscopy technique, paying special attention to issues that arise when the environmental noise is non-Gaussian and/or it has truly quantum properties. While we focus on the theoretical basis of the method, we connect the discussed concepts with specific experiments, and provide an overview of environmental noise models relevant for solid-state based qubits, including quantum-dot based spin qubits, superconducting qubits, and NV centers in diamond.
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Affiliation(s)
- P Szańkowski
- Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02668 Warsaw, Poland
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16
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Friesen M, Ghosh J, Eriksson MA, Coppersmith SN. A decoherence-free subspace in a charge quadrupole qubit. Nat Commun 2017; 8:15923. [PMID: 28643778 PMCID: PMC5490009 DOI: 10.1038/ncomms15923] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 05/15/2017] [Indexed: 12/03/2022] Open
Abstract
Quantum computing promises significant speed-up for certain types of computational problems. However, robust implementations of semiconducting qubits must overcome the effects of charge noise that currently limit coherence during gate operations. Here we describe a scheme for protecting solid-state qubits from uniform electric field fluctuations by generalizing the concept of a decoherence-free subspace for spins, and we propose a specific physical implementation: a quadrupole charge qubit formed in a triple quantum dot. The unique design of the quadrupole qubit enables a particularly simple pulse sequence for suppressing the effects of noise during gate operations. Simulations yield gate fidelities 10-1,000 times better than traditional charge qubits, depending on the magnitude of the environmental noise. Our results suggest that any qubit scheme employing Coulomb interactions (for example, encoded spin qubits or two-qubit gates) could benefit from such a quadrupolar design.
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Affiliation(s)
- Mark Friesen
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Joydip Ghosh
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M. A. Eriksson
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S. N. Coppersmith
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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17
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Boss JM, Cujia KS, Zopes J, Degen CL. Quantum sensing with arbitrary frequency resolution. Science 2017; 356:837-840. [DOI: 10.1126/science.aam7009] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 04/20/2017] [Indexed: 01/24/2023]
Affiliation(s)
- J. M. Boss
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
| | - K. S. Cujia
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
| | - J. Zopes
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
| | - C. L. Degen
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
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18
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Quintana CM, Chen Y, Sank D, Petukhov AG, White TC, Kafri D, Chiaro B, Megrant A, Barends R, Campbell B, Chen Z, Dunsworth A, Fowler AG, Graff R, Jeffrey E, Kelly J, Lucero E, Mutus JY, Neeley M, Neill C, O'Malley PJJ, Roushan P, Shabani A, Smelyanskiy VN, Vainsencher A, Wenner J, Neven H, Martinis JM. Observation of Classical-Quantum Crossover of 1/f Flux Noise and Its Paramagnetic Temperature Dependence. PHYSICAL REVIEW LETTERS 2017; 118:057702. [PMID: 28211704 DOI: 10.1103/physrevlett.118.057702] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Indexed: 06/06/2023]
Abstract
By analyzing the dissipative dynamics of a tunable gap flux qubit, we extract both sides of its two-sided environmental flux noise spectral density over a range of frequencies around 2k_{B}T/h≈1 GHz, allowing for the observation of a classical-quantum crossover. Below the crossover point, the symmetric noise component follows a 1/f power law that matches the magnitude of the 1/f noise near 1 Hz. The antisymmetric component displays a 1/T dependence below 100 mK, providing dynamical evidence for a paramagnetic environment. Extrapolating the two-sided spectrum predicts the linewidth and reorganization energy of incoherent resonant tunneling between flux qubit wells.
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Affiliation(s)
- C M Quintana
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - Yu Chen
- Google Inc., Santa Barbara, California 93117, USA
| | - D Sank
- Google Inc., Santa Barbara, California 93117, USA
| | - A G Petukhov
- NASA Ames Research Center, Moffett Field, California 94035, USA
| | - T C White
- Google Inc., Santa Barbara, California 93117, USA
| | - Dvir Kafri
- Google Inc., Venice, California 90291, USA
| | - B Chiaro
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - A Megrant
- Google Inc., Santa Barbara, California 93117, USA
| | - R Barends
- Google Inc., Santa Barbara, California 93117, USA
| | - B Campbell
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - Z Chen
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - A Dunsworth
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - A G Fowler
- Google Inc., Santa Barbara, California 93117, USA
| | - R Graff
- Google Inc., Santa Barbara, California 93117, USA
| | - E Jeffrey
- Google Inc., Santa Barbara, California 93117, USA
| | - J Kelly
- Google Inc., Santa Barbara, California 93117, USA
| | - E Lucero
- Google Inc., Santa Barbara, California 93117, USA
| | - J Y Mutus
- Google Inc., Santa Barbara, California 93117, USA
| | - M Neeley
- Google Inc., Santa Barbara, California 93117, USA
| | - C Neill
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - P J J O'Malley
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - P Roushan
- Google Inc., Santa Barbara, California 93117, USA
| | - A Shabani
- Google Inc., Venice, California 90291, USA
| | | | | | - J Wenner
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - H Neven
- Google Inc., Venice, California 90291, USA
| | - John M Martinis
- Department of Physics, University of California, Santa Barbara, California 93106, USA
- Google Inc., Santa Barbara, California 93117, USA
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19
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Laucht A, Kalra R, Simmons S, Dehollain JP, Muhonen JT, Mohiyaddin FA, Freer S, Hudson FE, Itoh KM, Jamieson DN, McCallum JC, Dzurak AS, Morello A. A dressed spin qubit in silicon. NATURE NANOTECHNOLOGY 2017; 12:61-66. [PMID: 27749833 DOI: 10.1038/nnano.2016.178] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 08/17/2016] [Indexed: 06/06/2023]
Abstract
Coherent dressing of a quantum two-level system provides access to a new quantum system with improved properties-a different and easily tunable level splitting, faster control and longer coherence times. In our work we investigate the properties of the dressed, donor-bound electron spin in silicon, and assess its potential as a quantum bit in scalable architectures. The two dressed spin-polariton levels constitute a quantum bit that can be coherently driven with an oscillating magnetic field, an oscillating electric field, frequency modulation of the driving field or a simple detuning pulse. We measure coherence times of and , one order of magnitude longer than those of the undressed spin. Furthermore, the use of the dressed states enables coherent coupling of the solid-state spins to electric fields and mechanical oscillations.
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Affiliation(s)
- Arne Laucht
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Rachpon Kalra
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Stephanie Simmons
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Juan P Dehollain
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Juha T Muhonen
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Fahd A Mohiyaddin
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Solomon Freer
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Fay E Hudson
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Kohei M Itoh
- School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kanagawa 223-8522, Japan
| | - David N Jamieson
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Jeffrey C McCallum
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Andrew S Dzurak
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - A Morello
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
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20
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21
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Yan F, Gustavsson S, Kamal A, Birenbaum J, Sears AP, Hover D, Gudmundsen TJ, Rosenberg D, Samach G, Weber S, Yoder JL, Orlando TP, Clarke J, Kerman AJ, Oliver WD. The flux qubit revisited to enhance coherence and reproducibility. Nat Commun 2016; 7:12964. [PMID: 27808092 PMCID: PMC5097147 DOI: 10.1038/ncomms12964] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 08/19/2016] [Indexed: 11/09/2022] Open
Abstract
The scalable application of quantum information science will stand on reproducible and controllable high-coherence quantum bits (qubits). Here, we revisit the design and fabrication of the superconducting flux qubit, achieving a planar device with broad-frequency tunability, strong anharmonicity, high reproducibility and relaxation times in excess of 40 μs at its flux-insensitive point. Qubit relaxation times T1 across 22 qubits are consistently matched with a single model involving resonator loss, ohmic charge noise and 1/f-flux noise, a noise source previously considered primarily in the context of dephasing. We furthermore demonstrate that qubit dephasing at the flux-insensitive point is dominated by residual thermal-photons in the readout resonator. The resulting photon shot noise is mitigated using a dynamical decoupling protocol, resulting in T2≈85 μs, approximately the 2T1 limit. In addition to realizing an improved flux qubit, our results uniquely identify photon shot noise as limiting T2 in contemporary qubits based on transverse qubit-resonator interaction.
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Affiliation(s)
- Fei Yan
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Simon Gustavsson
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Archana Kamal
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jeffrey Birenbaum
- Department of Physics, University of California, Berkeley, California 94720-7300, USA
| | - Adam P Sears
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - David Hover
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Ted J. Gudmundsen
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Danna Rosenberg
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Gabriel Samach
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - S Weber
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Jonilyn L. Yoder
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Terry P. Orlando
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - John Clarke
- Department of Physics, University of California, Berkeley, California 94720-7300, USA
| | - Andrew J. Kerman
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - William D. Oliver
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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22
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Takeda K, Kamioka J, Otsuka T, Yoneda J, Nakajima T, Delbecq MR, Amaha S, Allison G, Kodera T, Oda S, Tarucha S. A fault-tolerant addressable spin qubit in a natural silicon quantum dot. SCIENCE ADVANCES 2016; 2:e1600694. [PMID: 27536725 PMCID: PMC4982751 DOI: 10.1126/sciadv.1600694] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 07/12/2016] [Indexed: 05/18/2023]
Abstract
Fault-tolerant quantum computing requires high-fidelity qubits. This has been achieved in various solid-state systems, including isotopically purified silicon, but is yet to be accomplished in industry-standard natural (unpurified) silicon, mainly as a result of the dephasing caused by residual nuclear spins. This high fidelity can be achieved by speeding up the qubit operation and/or prolonging the dephasing time, that is, increasing the Rabi oscillation quality factor Q (the Rabi oscillation decay time divided by the π rotation time). In isotopically purified silicon quantum dots, only the second approach has been used, leaving the qubit operation slow. We apply the first approach to demonstrate an addressable fault-tolerant qubit using a natural silicon double quantum dot with a micromagnet that is optimally designed for fast spin control. This optimized design allows access to Rabi frequencies up to 35 MHz, which is two orders of magnitude greater than that achieved in previous studies. We find the optimum Q = 140 in such high-frequency range at a Rabi frequency of 10 MHz. This leads to a qubit fidelity of 99.6% measured via randomized benchmarking, which is the highest reported for natural silicon qubits and comparable to that obtained in isotopically purified silicon quantum dot-based qubits. This result can inspire contributions to quantum computing from industrial communities.
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Affiliation(s)
- Kenta Takeda
- RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan
- Corresponding author.
| | - Jun Kamioka
- Department of Physical Electronics and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Tomohiro Otsuka
- RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan
| | - Jun Yoneda
- RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan
| | - Takashi Nakajima
- RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan
| | - Matthieu R. Delbecq
- RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan
| | - Shinichi Amaha
- RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan
| | - Giles Allison
- RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan
| | - Tetsuo Kodera
- Department of Physical Electronics and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Shunri Oda
- Department of Physical Electronics and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Seigo Tarucha
- RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan
- Department of Applied Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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23
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Kapit E. Hardware-Efficient and Fully Autonomous Quantum Error Correction in Superconducting Circuits. PHYSICAL REVIEW LETTERS 2016; 116:150501. [PMID: 27127945 DOI: 10.1103/physrevlett.116.150501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Indexed: 06/05/2023]
Abstract
Superconducting qubits are among the most promising platforms for building a quantum computer. However, individual qubit coherence times are not far past the scalability threshold for quantum error correction, meaning that millions of physical devices would be required to construct a useful quantum computer. Consequently, further increases in coherence time are very desirable. In this Letter, we blueprint a simple circuit consisting of two transmon qubits and two additional lossy qubits or resonators, which is passively protected against all single-qubit quantum error channels through a combination of continuous driving and engineered dissipation. Photon losses are rapidly corrected through two-photon drive fields implemented with driven superconducting quantum interference device couplings, and dephasing from random potential fluctuations is heavily suppressed by the drive fields used to implement the multiqubit Hamiltonian. Comparing our theoretical model to published noise estimates from recent experiments on flux and transmon qubits, we find that logical state coherence could be improved by a factor of 40 or more compared to the individual qubit T_{1} and T_{2} using this technique. We thus demonstrate that there is substantial headroom for improving the coherence of modern superconducting qubits with a fairly modest increase in device complexity.
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Affiliation(s)
- Eliot Kapit
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA and Initiative for Theoretical Science, The Graduate Center, City University of New York, New York, New York 10016, USA
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24
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Norris LM, Paz-Silva GA, Viola L. Qubit Noise Spectroscopy for Non-Gaussian Dephasing Environments. PHYSICAL REVIEW LETTERS 2016; 116:150503. [PMID: 27127947 DOI: 10.1103/physrevlett.116.150503] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Indexed: 06/05/2023]
Abstract
We introduce open-loop quantum control protocols for characterizing the spectral properties of non-Gaussian noise, applicable to both classical and quantum dephasing environments. By engineering a multidimensional frequency comb via repetition of suitably designed pulse sequences, the desired high-order spectra may be related to observable properties of the qubit probe. We prove that access to a high time resolution is key to achieving spectral reconstruction over an extended bandwidth, overcoming the limitations of existing schemes. Non-Gaussian spectroscopy is demonstrated for a classical noise model describing quadratic dephasing at an optimal point, as well as a quantum spin-boson model out of equilibrium. In both cases, we obtain spectral reconstructions that accurately predict the qubit dynamics in the non-Gaussian regime.
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Affiliation(s)
- Leigh M Norris
- Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755, USA
| | - Gerardo A Paz-Silva
- Centre for Quantum Dynamics and Centre for Quantum Computation and Communication Technology, Griffith University, Brisbane, Queensland 4111, Australia
| | - Lorenza Viola
- Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755, USA
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25
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Gong M, Wen X, Sun G, Zhang DW, Lan D, Zhou Y, Fan Y, Liu Y, Tan X, Yu H, Yu Y, Zhu SL, Han S, Wu P. Simulating the Kibble-Zurek mechanism of the Ising model with a superconducting qubit system. Sci Rep 2016; 6:22667. [PMID: 26951775 PMCID: PMC4782105 DOI: 10.1038/srep22667] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 02/15/2016] [Indexed: 11/19/2022] Open
Abstract
The Kibble-Zurek mechanism (KZM) predicts the density of topological defects produced in the dynamical processes of phase transitions in systems ranging from cosmology to condensed matter and quantum materials. The similarity between KZM and the Landau-Zener transition (LZT), which is a standard tool to describe the dynamics of some non-equilibrium physics in contemporary physics, is being extensively exploited. Here we demonstrate the equivalence between KZM in the Ising model and LZT in a superconducting qubit system. We develop a time-resolved approach to study quantum dynamics of LZT with nano-second resolution. By using this technique, we simulate the key features of KZM in the Ising model with LZT, e.g., the boundary between the adiabatic and impulse regions, the freeze-out phenomenon in the impulse region, especially, the scaling law of the excited state population as the square root of the quenching speed. Our results provide the experimental evidence of the close connection between KZM and LZT, two textbook paradigms to study the dynamics of the non-equilibrium phenomena.
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Affiliation(s)
- Ming Gong
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China.,Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA
| | - Xueda Wen
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Guozhu Sun
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Dan-Wei Zhang
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, SPTE, South China Normal University, Guangzhou 510006, China
| | - Dong Lan
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Yu Zhou
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Yunyi Fan
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Yuhao Liu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Xinsheng Tan
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Haifeng Yu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yang Yu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shi-Liang Zhu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Siyuan Han
- Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA
| | - Peiheng Wu
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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26
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Ferrie C, Combes J. Weak value amplification is suboptimal for estimation and detection. PHYSICAL REVIEW LETTERS 2014; 112:040406. [PMID: 24580424 DOI: 10.1103/physrevlett.112.040406] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Indexed: 06/03/2023]
Abstract
We show by using statistically rigorous arguments that the technique of weak value amplification does not perform better than standard statistical techniques for the tasks of single parameter estimation and signal detection. Specifically, we prove that postselection, a necessary ingredient for weak value amplification, decreases estimation accuracy and, moreover, arranging for anomalously large weak values is a suboptimal strategy. In doing so, we explicitly provide the optimal estimator, which in turn allows us to identify the optimal experimental arrangement to be the one in which all outcomes have equal weak values (all as small as possible) and the initial state of the meter is the maximal eigenvalue of the square of the system observable. Finally, we give precise quantitative conditions for when weak measurement (measurements without postselection or anomalously large weak values) can mitigate the effect of uncharacterized technical noise in estimation.
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Affiliation(s)
- Christopher Ferrie
- Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA
| | - Joshua Combes
- Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA
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