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Zhao J, Jeng H, Conlon LO, Tserkis S, Shajilal B, Liu K, Ralph TC, Assad SM, Lam PK. Enhancing quantum teleportation efficacy with noiseless linear amplification. Nat Commun 2023; 14:4745. [PMID: 37550329 PMCID: PMC10406873 DOI: 10.1038/s41467-023-40438-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 07/28/2023] [Indexed: 08/09/2023] Open
Abstract
Quantum teleportation constitutes a fundamental tool for various applications in quantum communication and computation. However, state-of-the-art continuous-variable quantum teleportation is restricted to moderate fidelities and short-distance configurations. This is due to unavoidable experimental imperfections resulting in thermal decoherence during the teleportation process. Here we present a heralded quantum teleporter able to overcome these limitations through noiseless linear amplification. As a result, we report a high fidelity of 92% for teleporting coherent states using a modest level of quantum entanglement. Our teleporter in principle allows nearly complete removal of loss induced onto the input states being transmitted through imperfect quantum channels. We further demonstrate the purification of a displaced thermal state, impossible via conventional deterministic amplification or teleportation approaches. The combination of high-fidelity coherent state teleportation alongside the purification of thermalized input states permits the transmission of quantum states over significantly long distances. These results are of both practical and fundamental significance; overcoming long-standing hurdles en route to highly-efficient continuous-variable quantum teleportation, while also shining new light on applying teleportation to purify quantum systems from thermal noise.
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Affiliation(s)
- Jie Zhao
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
- Joint Quantum Institute, National Institute of Standard and Technology and University of Maryland, College park, 20742, MD, USA
| | - Hao Jeng
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Lorcán O Conlon
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Spyros Tserkis
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Biveen Shajilal
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Kui Liu
- State key laboratory of quantum optics and quantum optics devices, Institute of Opto-Electronics, Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006, Taiyuan, China
| | - Timothy C Ralph
- Centre for Quantum Computation and Communication Technology, School of Mathematics and Physics, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Syed M Assad
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Ping Koy Lam
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia.
- Institute of Materials Research and Engineering, Agency for Science Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, 138634, Singapore.
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Shajilal B, Huntington E, Lam PK, Assad S. A new entropic quantum correlation measure for adversarial systems. Sci Rep 2023; 13:1436. [PMID: 36697454 PMCID: PMC9877017 DOI: 10.1038/s41598-023-28035-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 01/11/2023] [Indexed: 01/26/2023] Open
Abstract
Quantum correlation often refers to correlations exhibited by two or more local subsystems under a suitable measurement. These correlations are beyond the framework of classical statistics and the associated classical probability distribution. Quantum entanglement is the most well-known of such correlations and plays an important role in quantum information theory. However, there exist non-entangled states that still possess quantum correlations which cannot be described by classical statistics. One such measure that captures these non-classical correlations is discord. Here we introduce a new measure of quantum correlations which we call entropic accord that fits between entanglement and discord. It is defined as the optimised minimax mutual information of the outcome of the projective measurements between two parties. We show a strict hierarchy exists between entanglement, entropic accord and discord for two-qubit states. We study two-qubit states which shows the relationship between the three entropic quantities. In addition to revealing a class of correlations that are distinct from discord and entanglement, the entropic accord measure can be inherently more intuitive in certain contexts.
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Affiliation(s)
- Biveen Shajilal
- grid.1001.00000 0001 2180 7477Centre for Quantum Computation and Communication Technology, Research School of Engineering, The Australian National University, Canberra, ACT 2601 Australia ,grid.1001.00000 0001 2180 7477Centre for Quantum Computation and Communication Technology, Department of Quantum Science, The Australian National University, Canberra, ACT 2601 Australia
| | - Elanor Huntington
- grid.1001.00000 0001 2180 7477Centre for Quantum Computation and Communication Technology, Research School of Engineering, The Australian National University, Canberra, ACT 2601 Australia
| | - Ping Koy Lam
- grid.1001.00000 0001 2180 7477Centre for Quantum Computation and Communication Technology, Department of Quantum Science, The Australian National University, Canberra, ACT 2601 Australia ,grid.59025.3b0000 0001 2224 0361School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 639673 Republic of Singapore ,grid.418788.a0000 0004 0470 809XInstitute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore, 138634 Republic of Singapore
| | - Syed Assad
- grid.1001.00000 0001 2180 7477Centre for Quantum Computation and Communication Technology, Department of Quantum Science, The Australian National University, Canberra, ACT 2601 Australia ,grid.59025.3b0000 0001 2224 0361School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 639673 Republic of Singapore
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Shajilal B, Thearle O, Tranter A, Lu Y, Huntington E, Assad S, Lam PK, Janousek J. 12.6 dB squeezed light at 1550 nm from a bow-tie cavity for long-term high duty cycle operation. Opt Express 2022; 30:37213-37223. [PMID: 36258313 DOI: 10.1364/oe.465521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Squeezed states are an interesting class of quantum states that have numerous applications. This work presents the design, characterization, and operation of a bow-tie optical parametric amplifier (OPA) for squeezed vacuum generation. We report the high duty cycle operation and long-term stability of the system that makes it suitable for post-selection based continuous-variable quantum information protocols, cluster-state quantum computing, quantum metrology, and potentially gravitational wave detectors. Over a 50 hour continuous operation, the measured squeezing levels were greater than 10 dB with a duty cycle of 96.6%. Alternatively, in a different mode of operation, the squeezer can also operate 10 dB below the quantum noise limit over a 12 hour period with no relocks, with an average squeezing of 11.9 dB. We also measured a maximum squeezing level of 12.6 dB at 1550 nm. This represents one of the best reported squeezing results at 1550 nm to date for a bow-tie cavity. We discuss the design aspects of the experiment that contribute to the overall stability, reliability, and longevity of the OPA, along with the automated locking schemes and different modes of operation.
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Enzian G, Freisem L, Price JJ, Svela AØ, Clarke J, Shajilal B, Janousek J, Buchler BC, Lam PK, Vanner MR. Non-Gaussian Mechanical Motion via Single and Multiphonon Subtraction from a Thermal State. Phys Rev Lett 2021; 127:243601. [PMID: 34951800 DOI: 10.1103/physrevlett.127.243601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 11/08/2021] [Indexed: 06/14/2023]
Abstract
Quantum optical measurement techniques offer a rich avenue for quantum control of mechanical oscillators via cavity optomechanics. In particular, a powerful yet little explored combination utilizes optical measurements to perform heralded non-Gaussian mechanical state preparation followed by tomography to determine the mechanical phase-space distribution. Here, we experimentally perform heralded single-phonon and multiphonon subtraction via photon counting to a laser-cooled mechanical thermal state with a Brillouin optomechanical system at room temperature and use optical heterodyne detection to measure the s-parametrized Wigner distribution of the non-Gaussian mechanical states generated. The techniques developed here advance the state of the art for optics-based tomography of mechanical states and will be useful for a broad range of applied and fundamental studies that utilize mechanical quantum-state engineering and tomography.
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Affiliation(s)
- G Enzian
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
- Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - L Freisem
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - J J Price
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - A Ø Svela
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
- Max Planck Institute for the Science of Light, Staudtstaße 2, 91058 Erlangen, Germany
| | - J Clarke
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - B Shajilal
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - J Janousek
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - B C Buchler
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - P K Lam
- Centre for Quantum Computation and Communication Technology, Research School of Physics and Engineering, Australian National University, Canberra 2601, Australia
| | - M R Vanner
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
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Lal N, Shajilal B, Anwar A, Perumangatt C, Singh RP. Observing sub-Poissonian statistics of twisted single photons using oscilloscope. Rev Sci Instrum 2019; 90:113104. [PMID: 31779388 DOI: 10.1063/1.5109544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 11/03/2019] [Indexed: 06/10/2023]
Abstract
Heralded single photon sources (HSPSs) from spontaneous parametric down-conversion are widely used as single photon sources. We study the photon number statistics of an HSPS carrying orbital angular momentum in our laboratory and observe the sub-Poissonian statistics using only photodetectors and an oscilloscope.
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Affiliation(s)
- Nijil Lal
- Physical Research Laboratory, Ahmedabad 380009, India
| | - Biveen Shajilal
- Cochin University of Science and Technology, Kochi 682022, India
| | - Ali Anwar
- Physical Research Laboratory, Ahmedabad 380009, India
| | | | - R P Singh
- Physical Research Laboratory, Ahmedabad 380009, India
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