1
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Ho LB. Quantum backaction effects in sequential measurements. ANNALS OF PHYSICS 2023; 453:169310. [DOI: 10.1016/j.aop.2023.169310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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2
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Okamoto R, Cohen E. Experimentally probing anomalous time evolution of a single photon. PNAS NEXUS 2023; 2:pgad157. [PMID: 37265544 PMCID: PMC10230160 DOI: 10.1093/pnasnexus/pgad157] [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: 11/14/2022] [Revised: 04/26/2023] [Accepted: 05/01/2023] [Indexed: 06/03/2023]
Abstract
In quantum mechanics, a quantum system is irreversibly collapsed by a projective measurement. Hence, delicately probing the time evolution of a quantum system holds the key to understanding curious phenomena. Here, we experimentally explore an anomalous time evolution, where, illustratively, a particle disappears from a box and emerges in a different box, with a certain moment in which it can be found in neither of them. In this experiment, we directly probe this curious time evolution of a single photon by measuring up to triple-operator sequential weak values (SWVs) using a novel probeless scheme. The naive interpretation provided by single-operator weak values (WVs) seems to imply the "disappearance" and "re-appearance" of a photon as theoretically predicted. However, double- and triple-operator SWVs, representing temporal correlations between the aforementioned values, show that spatial information about the photon does not entirely vanish in the intermediate time. These results show that local values (in space and time) alone, such as single-operator WVs, cannot fully explain all types of quantum evolution in time-higher order correlations are necessary in general, shedding new light on time evolution in quantum mechanics. The probeless measurement technique proposed here for measuring multiple-operator WVs can be straightforwardly extended to study various other cases of curious quantum evolution in time.
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Affiliation(s)
- Ryo Okamoto
- Department of Electronic Science and Engineering, Kyoto University, Kyoto Daigaku-Katsura, Nishikyo-ku, 615-8510 Kyoto, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, 332-0012 Saitama, Japan
| | - Eliahu Cohen
- Faculty of Engineering and Institute of Nanotechnology and Advanced Materials, Bar Ilan University, 5290002 Ramat Gan, Israel
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3
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Gaikwad A, Shende K, Arvind, Dorai K. Implementing efficient selective quantum process tomography of superconducting quantum gates on IBM quantum experience. Sci Rep 2022; 12:3688. [PMID: 35256689 PMCID: PMC8901781 DOI: 10.1038/s41598-022-07721-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 02/23/2022] [Indexed: 11/08/2022] Open
Abstract
The experimental implementation of selective quantum process tomography (SQPT) involves computing individual elements of the process matrix with the help of a special set of states called quantum 2-design states. However, the number of experimental settings required to prepare input states from quantum 2-design states to selectively and precisely compute a desired element of the process matrix is still high, and hence constructing the corresponding unitary operations in the lab is a daunting task. In order to reduce the experimental complexity, we mathematically reformulated the standard SQPT problem, which we term the modified SQPT (MSQPT) method. We designed the generalized quantum circuit to prepare the required set of input states and formulated an efficient measurement strategy aimed at minimizing the experimental cost of SQPT. We experimentally demonstrated the MSQPT protocol on the IBM QX2 cloud quantum processor and selectively characterized various two- and three-qubit quantum gates.
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Affiliation(s)
- Akshay Gaikwad
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81 SAS Nagar, Manauli, Punjab, 14030, India
| | - Krishna Shende
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81 SAS Nagar, Manauli, Punjab, 14030, India
| | - Arvind
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81 SAS Nagar, Manauli, Punjab, 14030, India
- Punjabi University, Patiala, Punjab, 147002, India
| | - Kavita Dorai
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81 SAS Nagar, Manauli, Punjab, 14030, India.
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4
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Fang W, Li J, Wei M, Zhang CH, Wang Q. Proof-of-principle demonstration of sequential 3 → 1 quantum random access code via cascaded measurements. OPTICS EXPRESS 2022; 30:8126-8135. [PMID: 35299560 DOI: 10.1364/oe.450349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 02/16/2022] [Indexed: 06/14/2023]
Abstract
Quantum random access code (QRAC) serves the communication task to encode a long message into a quantum system and allow the receiver to decode the initial information with a higher success probability than classical random access code (RAC). Here, we present an experimental demonstration of sequential 3 → 1 QRAC in the prepare-transform-measure scenario with one sender and three independent receivers. The experimental results show that, in the 3 → 1 QRAC scenario, three receivers can independently decode the initial information with an average success probability higher than the classical RAC.
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5
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Kim Y, Yoo SY, Kim YH. Heisenberg-Limited Metrology via Weak-Value Amplification without Using Entangled Resources. PHYSICAL REVIEW LETTERS 2022; 128:040503. [PMID: 35148150 DOI: 10.1103/physrevlett.128.040503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
Weak-value amplification (WVA) provides a way for amplified detection of a tiny physical signal at the expense of a lower detection probability. Despite this trade-off, due to its robustness against certain types of noise, WVA has advantages over conventional measurements in precision metrology. Moreover, it has been shown that WVA-based metrology can reach the Heisenberg limit using entangled resources, but preparing macroscopic entangled resources remains challenging. Here, we demonstrate a novel WVA scheme based on iterative interactions, achieving the Heisenberg-limited precision scaling without resorting to entanglement. This indicates that the perceived advantages of the entanglement-assisted WVA are in fact due to iterative interactions between each particle of an entangled system and a meter, rather than coming from the entanglement itself. Our work opens a practical pathway for achieving the Heisenberg-limited WVA without using fragile and experimentally demanding entangled resources.
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Affiliation(s)
- Yosep Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Seung-Yeun Yoo
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Yoon-Ho Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
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6
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Xu L, Xu H, Jiang T, Xu F, Zheng K, Wang B, Zhang A, Zhang L. Direct Characterization of Quantum Measurements Using Weak Values. PHYSICAL REVIEW LETTERS 2021; 127:180401. [PMID: 34767426 DOI: 10.1103/physrevlett.127.180401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/28/2021] [Accepted: 10/11/2021] [Indexed: 06/13/2023]
Abstract
The time-symmetric formalism endows the weak measurement and its outcome, the weak value, with many unique features. In particular, it allows a direct tomography of quantum states without resorting to complicated reconstruction algorithms and provides an operational meaning to wave functions and density matrices. Here, we propose and experimentally demonstrate the direct tomography of a measurement apparatus by taking the backward direction of weak measurement formalism. Our protocol works rigorously with the arbitrary measurement strength, which offers improved accuracy and precision. The precision can be further improved by taking into account the completeness condition of the measurement operators, which also ensures the feasibility of our protocol for the characterization of the arbitrary quantum measurement. Our work provides new insight on the symmetry between quantum states and measurements, as well as an efficient method to characterize a measurement apparatus.
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Affiliation(s)
- Liang Xu
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Research Center for Quantum Sensing, Zhejiang Lab, Hangzhou 310000, China
| | - Huichao Xu
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Purple Mountain Laboratories, Nanjing, Jiangsu 211111, China
| | - Tao Jiang
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Feixiang Xu
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Kaimin Zheng
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Ben Wang
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Aonan Zhang
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Lijian Zhang
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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7
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Arbitrary Configurable 20-Channel Coincidence Counting Unit for Multi-Qubit Quantum Experiment. ELECTRONICS 2021. [DOI: 10.3390/electronics10050569] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This paper presents a 20-channel coincidence counting unit (CCU) using a low-end field-programmable gate array (FPGA). The architecture of the CCU can be configured arbitrarily to measure from twofold to twentyfold coincidence counts thanks to a multifold controllable architecture, which can be easily manipulated by a graphical user interface (GUI) program. In addition, it provides up to 20 of each input signal count simultaneously. The experimental results show twentyfold coincidence counts with the resolution occurring in a less than 0.5 ns coincidence window. This CCU has appropriate characteristics for various quantum optics experiments using multi-photon qubits.
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8
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Lee GH, Im DG, Kim Y, Kim US, Kim YH. Observation of second-order interference beyond the coherence time with true thermal photons. OPTICS LETTERS 2020; 45:6748-6751. [PMID: 33325887 DOI: 10.1364/ol.413287] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 11/20/2020] [Indexed: 06/12/2023]
Abstract
It has recently been shown that counter-intuitive Franson-like second-order interference can be observed with a pair of classically correlated pseudo thermal light beams and two separate unbalanced interferometers (UIs): the second-order interference visibility remains fixed at 1/3 even though the path length difference in each UI is increased significantly beyond the coherence length of the pseudo thermal light [Phys. Rev. Lett.119, 223603 (2017)PRLTAO0031-900710.1103/PhysRevLett.119.223603]. However, as the pseudo thermal beam itself originated from a long-coherence laser (and by using a rotating ground disk), there exists the possibility of a classical theoretical model to account for second-order interference beyond the coherence time on the long coherence time of the original laser beam. In this work, we experimentally explore this counter-intuitive phenomenon with a true thermal photon source generated via quantum thermalization, i.e., obtaining a mixed state from a pure two-photon entangled state. This experiment not only demonstrates the unique second-order coherence properties of thermal light clearly but may also open up remote sensing applications based on such effects.
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9
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Wu KD, Bäumer E, Tang JF, Hovhannisyan KV, Perarnau-Llobet M, Xiang GY, Li CF, Guo GC. Minimizing Backaction through Entangled Measurements. PHYSICAL REVIEW LETTERS 2020; 125:210401. [PMID: 33275014 DOI: 10.1103/physrevlett.125.210401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 10/05/2020] [Indexed: 06/12/2023]
Abstract
When an observable is measured on an evolving coherent quantum system twice, the first measurement generally alters the statistics of the second one, which is known as measurement backaction. We introduce, and push to its theoretical and experimental limits, a novel method of backaction evasion, whereby entangled collective measurements are performed on several copies of the system. This method is inspired by a similar idea designed for the problem of measuring quantum work [Perarnau-Llobet et al., Phys. Rev. Lett. 118, 070601 (2017)PRLTAO0031-900710.1103/PhysRevLett.118.070601]. By using entanglement as a resource, we show that the backaction can be extremely suppressed compared to all previous schemes. Importantly, the backaction can be eliminated in highly coherent processes.
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Affiliation(s)
- Kang-Da Wu
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Elisa Bäumer
- Institute for Theoretical Physics, ETH Zurich, 8093 Zürich, Switzerland
| | - Jun-Feng Tang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Karen V Hovhannisyan
- The Abdus Salam International Centre for Theoretical Physics (ICTP), Strada Costiera 11, 34151 Trieste, Italy
| | | | - Guo-Yong Xiang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Chuan-Feng Li
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Guang-Can Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China
- CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
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10
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Li T, Wang Q, Taallah A, Zhang S, Yu T, Zhang Z. Measurement of the magnetic properties of thin films based on the spin Hall effect of light. OPTICS EXPRESS 2020; 28:29086-29097. [PMID: 33114814 DOI: 10.1364/oe.403831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 09/04/2020] [Indexed: 06/11/2023]
Abstract
Using the spin Hall effect of light, this work proposes a measurement technique of the magnetic properties of thin films. The beam shift of the spin Hall effect of light is used to replace the magneto-optical Kerr rotation angle as a parameter to characterize the magnetism of thin films. The technique can easily achieve an accuracy of 10-6 rad of the magneto-optical Kerr rotation angle which can, in theory, be further improved to 10-8 rad. We also proposed two methods to solve the problem of the exceeding linear response region of the measurement under high magnetic field intensity, making it more conducive to practical application. This technique has great potential for application in the magnetic measurement of ultra-thin films with particular emphasis on thicknesses within several atomic layers.
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11
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Anwer H, Muhammad S, Cherifi W, Miklin N, Tavakoli A, Bourennane M. Experimental Characterization of Unsharp Qubit Observables and Sequential Measurement Incompatibility via Quantum Random Access Codes. PHYSICAL REVIEW LETTERS 2020; 125:080403. [PMID: 32909802 DOI: 10.1103/physrevlett.125.080403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/30/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
Unsharp measurements are increasingly important for foundational insights in quantum theory and quantum information applications. Here, we report an experimental implementation of unsharp qubit measurements in a sequential communication protocol, based on a quantum random access code. The protocol involves three parties; the first party prepares a qubit system, the second party performs operations that return both a classical and quantum outcome, and the latter is measured by the third party. We demonstrate a nearly optimal sequential quantum random access code that outperforms both the best possible classical protocol and any quantum protocol that utilizes only projective measurements. Furthermore, while only assuming that the involved devices operate on qubits and that detected events constitute a fair sample, we demonstrate the noise-robust characterization of unsharp measurements based on the sequential quantum random access code. We apply this characterization towards quantifying the degree of incompatibility of two sequential pairs of quantum measurements.
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Affiliation(s)
- Hammad Anwer
- Department of Physics, Stockholm University, S-10691 Stockholm, Sweden
| | - Sadiq Muhammad
- Department of Physics, Stockholm University, S-10691 Stockholm, Sweden
| | - Walid Cherifi
- Department of Physics, Stockholm University, S-10691 Stockholm, Sweden
| | - Nikolai Miklin
- Institute of Theoretical Physics and Astrophysics, National Quantum Information Center, Faculty of Mathematics, Physics and Informatics, University of Gdansk, 80-952 Gdánsk, Poland
| | - Armin Tavakoli
- Département de Physique Appliquée, Université de Genève, CH-1211 Genève, Switzerland
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12
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Kim Y, Teo YS, Ahn D, Im DG, Cho YW, Leuchs G, Sánchez-Soto LL, Jeong H, Kim YH. Universal Compressive Characterization of Quantum Dynamics. PHYSICAL REVIEW LETTERS 2020; 124:210401. [PMID: 32530676 DOI: 10.1103/physrevlett.124.210401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
Recent quantum technologies utilize complex multidimensional processes that govern the dynamics of quantum systems. We develop an adaptive diagonal-element-probing compression technique that feasibly characterizes any unknown quantum processes using much fewer measurements compared to conventional methods. This technique utilizes compressive projective measurements that are generalizable to an arbitrary number of subsystems. Both numerical analysis and experimental results with unitary gates demonstrate low measurement costs, of order O(d^{2}) for d-dimensional systems, and robustness against statistical noise. Our work potentially paves the way for a reliable and highly compressive characterization of general quantum devices.
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Affiliation(s)
- Yosep Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), 37673 Pohang, Korea
| | - Yong Siah Teo
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Daekun Ahn
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Dong-Gil Im
- Department of Physics, Pohang University of Science and Technology (POSTECH), 37673 Pohang, Korea
| | - Young-Wook Cho
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), 02792 Seoul, Korea
| | - Gerd Leuchs
- Max-Planck-Institut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen, Germany
- Institute of Applied Physics, Russian Academy of Sciences, 603950 Nizhny Novgorod, Russia
| | - Luis L Sánchez-Soto
- Max-Planck-Institut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen, Germany
- Departamento de Óptica, Facultad de Física, Universidad Complutense, 28040 Madrid, Spain
| | - Hyunseok Jeong
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, Korea
| | - Yoon-Ho Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), 37673 Pohang, Korea
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13
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Reconstruction of quantum channel via convex optimization. Sci Bull (Beijing) 2020; 65:286-292. [PMID: 36659093 DOI: 10.1016/j.scib.2019.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/18/2019] [Accepted: 10/22/2019] [Indexed: 01/21/2023]
Abstract
Quantum process tomography is often used to completely characterize an unknown quantum process. However, it may lead to an unphysical process matrix, which will cause the loss of information with respect to the tomography result. Convex optimization, widely used in machine learning, is able to generate a global optimum that best fits the raw data while keeping the process tomography in a legitimate region. Only by correctly revealing the original action of the process can we seek deeper into its properties like its phase transition and its Hamiltonian. Here, we reconstruct the seawater channel using convex optimization and further test it on the seven fundamental gates. We compare our method to the standard-inversion and norm-optimization approaches using the cost function value and our proposed state deviation. The advantages convince that our method enables a more precise and robust estimation of the elements of the process matrix with less demands on preliminary resources. In addition, we examine on a set of non-unitary channels and the reconstructions reach up to 99.5% accuracy. Our method offers a more universal tool for further analyses on the components of the quantum channels and we believe that the crossover between quantum process tomography and convex optimization may help us move forward to machine learning of quantum channels.
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Chen JS, Hu MJ, Hu XM, Liu BH, Huang YF, Li CF, Guo CG, Zhang YS. Experimental realization of sequential weak measurements of non-commuting Pauli observables. OPTICS EXPRESS 2019; 27:6089-6097. [PMID: 30876202 DOI: 10.1364/oe.27.006089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 01/13/2019] [Indexed: 06/09/2023]
Abstract
Sequential weak measurements of non-commuting observables are not only fundamentally interesting in terms of quantum measurement but also show potential in various applications. Previously reported methods, however, can only make limited sequential weak measurements experimentally. In this article, we propose the realization of sequential measurements of non-commuting Pauli observables and experimentally demonstrate for the first time the measurement of sequential weak values of three non-commuting Pauli observables using genuine single photons.
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15
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Universality of local weak interactions and its application for interferometric alignment. Proc Natl Acad Sci U S A 2019; 116:2881-2890. [PMID: 30723153 PMCID: PMC6386691 DOI: 10.1073/pnas.1812970116] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The modification of the effect of interactions of a particle as a function of its preselected and postselected states is analyzed theoretically and experimentally. The universality property of this modification in the case of local interactions of a spatially preselected and postselected particle has been found. It allowed us to define an operational approach for the characterization of the presence of a quantum particle in a particular place: the way it modifies the effect of local interactions. The experiment demonstrating this universality property provides an efficient interferometric alignment method, in which the position of the beam on a single detector throughout one phase scan yields all misalignment parameters.
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16
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Kim YS, Pramanik T, Cho YW, Yang M, Han SW, Lee SY, Kang MS, Moon S. Informationally symmetrical Bell state preparation and measurement. OPTICS EXPRESS 2018; 26:29539-29549. [PMID: 30470116 DOI: 10.1364/oe.26.029539] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 10/10/2018] [Indexed: 06/09/2023]
Abstract
Bell state measurement (BSM) plays crucial roles in photonic quantum information processing. The standard linear optical BSM is based on Hong-Ou-Mandel interference where two photons meet and interfere at a beamsplitter (BS). However, a generalized two-photon interference is not based on photon-photon interaction, but interference between two-photon probability amplitudes. Therefore, it might be possible to implement BSM without interfering photons at a BS. Here, we investigate a linear optical BSM scheme which does not require two photon overlapping at a BS. By unleashing the two photon coexistence condition, it can be symmetrically divided into two parties. The symmetrically dividable property suggests an informationally symmetrical BSM between remote parties without a third party. We also present that our BSM scheme can be used for Bell state preparation between remote parties without a third party. Since our BSM scheme can be easily extended to multiple photons, it can be useful for various quantum communication applications.
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