51
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Guo Y, Hu XM, Hou ZB, Cao H, Cui JM, Liu BH, Huang YF, Li CF, Guo GC, Chiribella G. Experimental Transmission of Quantum Information Using a Superposition of Causal Orders. PHYSICAL REVIEW LETTERS 2020; 124:030502. [PMID: 32031864 DOI: 10.1103/physrevlett.124.030502] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/27/2019] [Indexed: 06/10/2023]
Abstract
Communication in a network generally takes place through a sequence of intermediate nodes connected by communication channels. In the standard theory of communication, it is assumed that the communication network is embedded in a classical spacetime, where the relative order of different nodes is well defined. In principle, a quantum theory of spacetime could allow the order of the intermediate points between sender and receiver to be in a coherent superposition. Here we experimentally realize a tabletop simulation of this exotic possibility on a photonic system, demonstrating high-fidelity transmission of quantum information over two noisy channels arranged in a superposition of two alternative causal orders.
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Affiliation(s)
- Yu 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
| | - Xiao-Min Hu
- 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
| | - Zhi-Bo Hou
- 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
| | - Huan Cao
- 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
| | - Jin-Ming Cui
- 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
| | - Bi-Heng Liu
- 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
| | - Yun-Feng Huang
- 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
| | - Giulio Chiribella
- Department of Computer Science, The University of Hong Kong, Pokfulam Road, Hong Kong 999077, People's Republic of China
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
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52
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Ornes S. News Feature: Quantum effects enter the macroworld. Proc Natl Acad Sci U S A 2019; 116:22413-22417. [PMID: 31690692 PMCID: PMC6842585 DOI: 10.1073/pnas.1917212116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023] Open
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53
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Reginatto M, Hall MJW. Entangling quantum fields via a classical gravitational interaction. ACTA ACUST UNITED AC 2019. [DOI: 10.1088/1742-6596/1275/1/012039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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54
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Restuccia S, Toroš M, Gibson GM, Ulbricht H, Faccio D, Padgett MJ. Photon Bunching in a Rotating Reference Frame. PHYSICAL REVIEW LETTERS 2019; 123:110401. [PMID: 31573252 DOI: 10.1103/physrevlett.123.110401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Indexed: 06/10/2023]
Abstract
Although quantum physics is well understood in inertial reference frames (flat spacetime), a current challenge is the search for experimental evidence of nontrivial or unexpected behavior of quantum systems in noninertial frames. Here, we present a novel test of quantum mechanics in a noninertial reference frame: we consider Hong-Ou-Mandel (HOM) interference on a rotating platform and study the effect of uniform rotation on the distinguishability of the photons. Both theory and experiments show that the rotational motion induces a relative delay in the photon arrival times at the exit beam splitter and that this delay is observed as a shift in the position of the HOM dip. This experiment can be extended to a full general relativistic test of quantum physics using satellites in Earth's orbit and indicates a new route toward the use of photonic technologies for investigating quantum mechanics at the interface with relativity.
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Affiliation(s)
- Sara Restuccia
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Marko Toroš
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Graham M Gibson
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Hendrik Ulbricht
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Daniele Faccio
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Miles J Padgett
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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55
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Zych M, Costa F, Pikovski I, Brukner Č. Bell's theorem for temporal order. Nat Commun 2019; 10:3772. [PMID: 31434883 PMCID: PMC6704104 DOI: 10.1038/s41467-019-11579-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 07/17/2019] [Indexed: 11/09/2022] Open
Abstract
Time has a fundamentally different character in quantum mechanics and in general relativity. In quantum theory events unfold in a fixed order while in general relativity temporal order is influenced by the distribution of matter. When matter requires a quantum description, temporal order is expected to become non-classical-a scenario beyond the scope of current theories. Here we provide a direct description of such a scenario. We consider a thought experiment with a massive body in a spatial superposition and show how it leads to entanglement of temporal orders between time-like events. This entanglement enables accomplishing a task, violation of a Bell inequality, that is impossible under local classical temporal order; it means that temporal order cannot be described by any pre-defined local variables. A classical notion of a causal structure is therefore untenable in any framework compatible with the basic principles of quantum mechanics and classical general relativity.
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Affiliation(s)
- Magdalena Zych
- Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St. Lucia, QLD, 4072, Australia.
| | - Fabio Costa
- Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Igor Pikovski
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138, USA.,Department of Physics, Harvard University, Cambridge, MA, 02138, USA.,Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - Časlav Brukner
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090, Vienna, Austria.,Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090, Vienna, Austria
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56
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Giampaolo SM, Macrì T. Entanglement, holonomic constraints, and the quantization of fundamental interactions. Sci Rep 2019; 9:11362. [PMID: 31388040 PMCID: PMC6684814 DOI: 10.1038/s41598-019-47844-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 07/16/2019] [Indexed: 11/12/2022] Open
Abstract
We provide a proof for the necessity of quantizing fundamental interactions demonstrating that a quantum version is needed for any non trivial conservative interaction whose strength depends on the relative distance between two objects. Our proof is based on a consistency argument that in the presence of a classical field two interacting objects in a separable state could not develop entanglement. This requirement can be cast in the form of a holonomic constraint that cannot be satisfied by generic interparticle potentials. Extending this picture of local holonomic constraints, we design a protocol that allows to measure the terms of a multipole expansion of the interaction of two composite bodies. The results presented in this work can pave the way for a study of fundamental interactions based on the analysis of entanglement properties.
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Affiliation(s)
- Salvatore Marco Giampaolo
- Division of Theoretical Physics, Rudjer Bošković Institute, Bijenčka cesta 54, 10000, Zagreb, Croatia
| | - Tommaso Macrì
- Departamento de Física Teórica e Experimental and International Institute of Physics, Universidade Federal do Rio Grande do Norte, 59072-970, Natal-RN, Brazil.
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57
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Matsumoto N, Cataño-Lopez SB, Sugawara M, Suzuki S, Abe N, Komori K, Michimura Y, Aso Y, Edamatsu K. Demonstration of Displacement Sensing of a mg-Scale Pendulum for mm- and mg-Scale Gravity Measurements. PHYSICAL REVIEW LETTERS 2019; 122:071101. [PMID: 30848624 DOI: 10.1103/physrevlett.122.071101] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/05/2018] [Indexed: 06/09/2023]
Abstract
Gravity generated by large masses has been observed using a variety of probes from atomic interferometers to torsional balances. However, gravitational coupling between small masses has never been observed so far. Here, we demonstrate sensitive displacement sensing of the Brownian motion of an optically trapped 7 mg pendulum motion whose natural quality factor is increased to 10^{8} through dissipation dilution. The sensitivity for an integration time of one second corresponds to the displacement generated in a millimeter-scale gravitational experiment between the probe and a 100 mg source mass, whose position is modulated at the pendulum mechanical resonant frequency. Development of such a sensitive displacement sensor using a milligram-scale device will pave the way for a new class of experiments where gravitational coupling between small masses in quantum regimes can be achieved.
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Affiliation(s)
- Nobuyuki Matsumoto
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
- JST, PRESTO, Kawaguchi, Saitama 332-0012, Japan
| | - Seth B Cataño-Lopez
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
| | - Masakazu Sugawara
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
| | - Seiya Suzuki
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
| | - Naofumi Abe
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
| | - Kentaro Komori
- Department of Physics, University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Yuta Michimura
- Department of Physics, University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Yoichi Aso
- National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan
- Department of Astronomical Science, SOKENDAI (The Graduate University for Advanced Studies), Mitaka, Tokyo 181-8588, Japan
| | - Keiichi Edamatsu
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
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58
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Marinković I, Wallucks A, Riedinger R, Hong S, Aspelmeyer M, Gröblacher S. Optomechanical Bell Test. PHYSICAL REVIEW LETTERS 2018; 121:220404. [PMID: 30547658 DOI: 10.1103/physrevlett.121.220404] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Indexed: 06/09/2023]
Abstract
Over the past few decades, experimental tests of Bell-type inequalities have been at the forefront of understanding quantum mechanics and its implications. These strong bounds on specific measurements on a physical system originate from some of the most fundamental concepts of classical physics-in particular that properties of an object are well-defined independent of measurements (realism) and only affected by local interactions (locality). The violation of these bounds unambiguously shows that the measured system does not behave classically, void of any assumption on the validity of quantum theory. It has also found applications in quantum technologies for certifying the suitability of devices for generating quantum randomness, distributing secret keys and for quantum computing. Here we report on the violation of a Bell inequality involving a massive, macroscopic mechanical system. We create light-matter entanglement between the vibrational motion of two silicon optomechanical oscillators, each comprising approx. 10^{10} atoms, and two optical modes. This state allows us to violate a Bell inequality by more than 4 standard deviations, directly confirming the nonclassical behavior of our optomechanical system under the fair sampling assumption.
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Affiliation(s)
- Igor Marinković
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628CJ Delft, Netherlands
| | - Andreas Wallucks
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628CJ Delft, Netherlands
| | - Ralf Riedinger
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, A-1090 Vienna, Austria
| | - Sungkun Hong
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, A-1090 Vienna, Austria
| | - Markus Aspelmeyer
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, A-1090 Vienna, Austria
| | - Simon Gröblacher
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628CJ Delft, Netherlands
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59
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Chen XY, Yin ZQ. High-precision gravimeter based on a nano-mechanical resonator hybrid with an electron spin. OPTICS EXPRESS 2018; 26:31577-31588. [PMID: 30650741 DOI: 10.1364/oe.26.031577] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/03/2018] [Indexed: 06/09/2023]
Abstract
We show that the gravitational acceleration can be measured with the matter-wave Ramsey interferometry, by using a nitrogen-vacancy center coupled to a nano-mechanical resonator. We propose two experimental methods to realize the similar Hamiltonian, by using either a cantilever resonator or a trapped nanoparticle. The scheme is robust against the thermal noise, and could be realized at the temperature much higher than the quantum regime. The effects of decoherence on the interferometry fringe visibility is calculated, considering both the mechanical motional decay and dephasing of the nitrogen-vacancy center. In addition, we demonstrate that under the various sources of random and systematic noises, our gravimeter can be made on-chip and achieve a high measurement of precision. Under experimental feasible parameters, the proposed gravimeter could achieve 10-10 relative precision.
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60
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Abstract
Quantum resolutions of the space-time singularity at the end of gravitational collapse may provide hints towards the properties of a final theory of Quantum-Gravity. The mechanism by which the singularity is avoided and replaced by a bounce depends on the specific behaviour of gravity in the strong field and may have implications for the geometry of the space-time also in the weak field. In the last few decades, several scenarios for black hole bounces have been proposed and I shall argue that the times are now mature to ask the question of whether such bounces can be observed in astrophysical phenomena.
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61
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Ahn J, Xu Z, Bang J, Deng YH, Hoang TM, Han Q, Ma RM, Li T. Optically Levitated Nanodumbbell Torsion Balance and GHz Nanomechanical Rotor. PHYSICAL REVIEW LETTERS 2018; 121:033603. [PMID: 30085795 DOI: 10.1103/physrevlett.121.033603] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Indexed: 05/23/2023]
Abstract
Levitated optomechanics has great potential in precision measurements, thermodynamics, macroscopic quantum mechanics, and quantum sensing. Here we synthesize and optically levitate silica nanodumbbells in high vacuum. With a linearly polarized laser, we observe the torsional vibration of an optically levitated nanodumbbell. This levitated nanodumbbell torsion balance is a novel analog of the Cavendish torsion balance, and provides rare opportunities to observe the Casimir torque and probe the quantum nature of gravity as proposed recently. With a circularly polarized laser, we drive a 170-nm-diameter nanodumbbell to rotate beyond 1 GHz, which is the fastest nanomechanical rotor realized to date. Smaller silica nanodumbbells can sustain higher rotation frequencies. Such ultrafast rotation may be used to study material properties and probe vacuum friction.
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Affiliation(s)
- Jonghoon Ahn
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | - Zhujing Xu
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
| | - Jaehoon Bang
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | - Yu-Hao Deng
- State Key Lab for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871, China
| | - Thai M Hoang
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
| | - Qinkai Han
- The State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Ren-Min Ma
- State Key Lab for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Tongcang Li
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
- Purdue Quantum Center, Purdue University, West Lafayette, Indiana 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
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