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Su ZE, Taitler B, Schwartz I, Cogan D, Nassar I, Kenneth O, Lindner NH, Gershoni D. Continuous and deterministic all-photonic cluster state of indistinguishable photons. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:077601. [PMID: 38957917 DOI: 10.1088/1361-6633/ad4c93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 05/16/2024] [Indexed: 07/04/2024]
Abstract
Cluster states are key resources for measurement-based quantum information processing. Photonic cluster and graph states, in particular, play indispensable roles in quantum network and quantum metrology. We demonstrate a semiconductor quantum dot based device in which the confined hole spin acts as a needle in a quantum knitting machine producing continuously and deterministically at sub-Gigahertz repetition rate single indistinguishable photons which are all polarization entangled to each other and to the spin in a one dimensional cluster state. By projecting two nonadjacent photons onto circular polarization bases we disentangle the spin from the photons emitted in between. This way we demonstrate a novel way for producing deterministic and continuous all-photonic cluster states. We use polarization tomography on four sequentially detected photons to demonstrate and to directly quantify the robustness of the cluster's entanglement and the determinism in its photon generation.
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Affiliation(s)
- Zu-En Su
- The Physics Department and the Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Boaz Taitler
- The Physics Department and the Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ido Schwartz
- The Physics Department and the Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Dan Cogan
- The Physics Department and the Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ismail Nassar
- The Physics Department and the Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Oded Kenneth
- The Physics Department and the Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Netanel H Lindner
- The Physics Department and the Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - David Gershoni
- The Physics Department and the Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
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2
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Thomas P, Ruscio L, Morin O, Rempe G. Fusion of deterministically generated photonic graph states. Nature 2024; 629:567-572. [PMID: 38720079 PMCID: PMC11096110 DOI: 10.1038/s41586-024-07357-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 03/26/2024] [Indexed: 05/18/2024]
Abstract
Entanglement has evolved from an enigmatic concept of quantum physics to a key ingredient of quantum technology. It explains correlations between measurement outcomes that contradict classical physics and has been widely explored with small sets of individual qubits. Multi-partite entangled states build up in gate-based quantum-computing protocols and-from a broader perspective-were proposed as the main resource for measurement-based quantum-information processing1,2. The latter requires the ex-ante generation of a multi-qubit entangled state described by a graph3-6. Small graph states such as Bell or linear cluster states have been produced with photons7-16, but the proposed quantum-computing and quantum-networking applications require fusion of such states into larger and more powerful states in a programmable fashion17-21. Here we achieve this goal by using an optical resonator22 containing two individually addressable atoms23,24. Ring25 and tree26 graph states with up to eight qubits, with the names reflecting the entanglement topology, are efficiently fused from the photonic states emitted by the individual atoms. The fusion process itself uses a cavity-assisted gate between the two atoms. Our technique is, in principle, scalable to even larger numbers of qubits and is the decisive step towards, for instance, a memory-less quantum repeater in a future quantum internet27-29.
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Affiliation(s)
- Philip Thomas
- Max-Planck-Institut für Quantenoptik, Garching, Germany
| | | | - Olivier Morin
- Max-Planck-Institut für Quantenoptik, Garching, Germany.
| | - Gerhard Rempe
- Max-Planck-Institut für Quantenoptik, Garching, Germany
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3
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Paesani S, Brown BJ. High-Threshold Quantum Computing by Fusing One-Dimensional Cluster States. PHYSICAL REVIEW LETTERS 2023; 131:120603. [PMID: 37802959 DOI: 10.1103/physrevlett.131.120603] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 07/11/2023] [Indexed: 10/08/2023]
Abstract
We propose a measurement-based model for fault-tolerant quantum computation that can be realized with one-dimensional cluster states and fusion measurements only; basic resources that are readily available with scalable photonic hardware. Our simulations demonstrate high thresholds compared with other measurement-based models realized with basic entangled resources and 2-qubit fusion measurements. Its high tolerance to noise indicates that our practical construction offers a promising route to scalable quantum computing with quantum emitters and linear-optical elements.
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Affiliation(s)
- Stefano Paesani
- Center for Hybrid Quantum Networks (Hy-Q), Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen 2100, Denmark
- NNF Quantum Computing Programme, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen 2100, Denmark
| | - Benjamin J Brown
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
- IBM Denmark, Prøvensvej 1, Brøndby 2605, Denmark
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Nasiri Avanaki K, Schatz GC. Generation of entangled-photons by a quantum dot cascade source in polarized cavities: Using cavity resonances to boost signals and preserve the entanglements. J Chem Phys 2023; 158:144106. [PMID: 37061505 DOI: 10.1063/5.0144364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
Motivated by recent advances in the development of single photon emitters for quantum information sciences, here we design and formulate a quantum cascade model that describes cascade emission by a quantum dot (QD) in a cavity structure while preserving entanglement that stores information needed for single photon emission. The theoretical approach is based on a photonic structure that consists of two orthogonal cavities in which resonance with either the first or second of the two emitted photons is possible, leading to amplification and rerouting of the entangled light. The cavity-QD scheme uses a four-level cascade emitter that involves three levels for each polarization, leading to two spatially entangled photons for each polarization. By solving the Schrodinger equation, we identify the characteristic properties of the system, which can be used in conjunction with optimization techniques to achieve the "best" design relative to a set of prioritized criteria or constraints in our optical system. The theoretical investigations include an analysis of emission spectra in addition to the joint spectral density profile, and the results demonstrate the ability of the cavities to act as frequency filters for the photons that make up the entanglements and to modify entanglement properties. The results provide new opportunities for the experimental design and engineering of on-demand single photon sources.
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Affiliation(s)
- K Nasiri Avanaki
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
| | - George C Schatz
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
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Cogan D, Su ZE, Kenneth O, Gershoni D. Deterministic generation of indistinguishable photons in a cluster state. NATURE PHOTONICS 2023; 17:324-329. [PMID: 37064524 PMCID: PMC10091623 DOI: 10.1038/s41566-022-01152-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 12/19/2022] [Indexed: 06/19/2023]
Abstract
Entanglement between particles is a basic concept of quantum sciences. The ability to produce entangled particles in a controllable manner is essential for any quantum technology. Entanglement between light particles (photons) is particularly crucial for quantum communication due to light's non-interactive nature and long-lasting coherence. Resources producing entangled multiphoton cluster states will enable communication between remote quantum nodes, as the inbuilt redundancy of cluster photons allows for repeated local measurements-compensating for losses and probabilistic Bell measurements. For feasible applications, the cluster generation should be fast, deterministic and, most importantly, its photons indistinguishable, which will allow measurements and fusion of clusters by interfering photons. Here, using periodic excitation of a semiconductor quantum-dot-confined spin, we demonstrate a multi-indistinguishable photon cluster, featuring a continuously generated string of photons at deterministic gigahertz generation rates, and an optimized entanglement length of about ten photons. The indistinguishability of the photons opens up new possibilities for scaling up the cluster's dimensionality by fusion, thus building graph states suited for measurement-based photonic quantum computers and all-photonic quantum repeaters.
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Affiliation(s)
- Dan Cogan
- The Physics Department and the Solid State Institute, Technion — Israel Institute of Technology, Haifa, Israel
| | - Zu-En Su
- The Physics Department and the Solid State Institute, Technion — Israel Institute of Technology, Haifa, Israel
| | - Oded Kenneth
- The Physics Department and the Solid State Institute, Technion — Israel Institute of Technology, Haifa, Israel
| | - David Gershoni
- The Physics Department and the Solid State Institute, Technion — Israel Institute of Technology, Haifa, Israel
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Efficient generation of entangled multiphoton graph states from a single atom. Nature 2022; 608:677-681. [PMID: 36002484 PMCID: PMC9402438 DOI: 10.1038/s41586-022-04987-5] [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: 01/26/2022] [Accepted: 06/16/2022] [Indexed: 11/23/2022]
Abstract
The central technological appeal of quantum science resides in exploiting quantum effects, such as entanglement, for a variety of applications, including computing, communication and sensing1. The overarching challenge in these fields is to address, control and protect systems of many qubits against decoherence2. Against this backdrop, optical photons, naturally robust and easy to manipulate, represent ideal qubit carriers. However, the most successful technique so far for creating photonic entanglement3 is inherently probabilistic and, therefore, subject to severe scalability limitations. Here we report the implementation of a deterministic protocol4–6 for the creation of photonic entanglement with a single memory atom in a cavity7. We interleave controlled single-photon emissions with tailored atomic qubit rotations to efficiently grow Greenberger–Horne–Zeilinger (GHZ) states8 of up to 14 photons and linear cluster states9 of up to 12 photons with a fidelity lower bounded by 76(6)% and 56(4)%, respectively. Thanks to a source-to-detection efficiency of 43.18(7)% per photon, we measure these large states about once every minute, which is orders of magnitude faster than in any previous experiment3,10–13. In the future, this rate could be increased even further, the scheme could be extended to two atoms in a cavity14,15 or several sources could be quantum mechanically coupled16, to generate higher-dimensional cluster states17. Overcoming the limitations encountered by probabilistic schemes for photonic entanglement generation, our results may offer a way towards scalable measurement-based quantum computation18,19 and communication20,21. Using a single memory atom in a cavity, a deterministic protocol is implemented to efficiently grow Greenberger–Horne–Zeilinger and linear cluster states by means of single-photon emissions.
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Multipartite Correlations in Quantum Collision Models. ENTROPY 2022; 24:e24040508. [PMID: 35455171 PMCID: PMC9032730 DOI: 10.3390/e24040508] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/01/2022] [Accepted: 04/03/2022] [Indexed: 12/10/2022]
Abstract
Quantum collision models have proved to be useful for a clear and concise description of many physical phenomena in the field of open quantum systems: thermalization, decoherence, homogenization, nonequilibrium steady state, entanglement generation, simulation of many-body dynamics, and quantum thermometry. A challenge in the standard collision model, where the system and many ancillas are all initially uncorrelated, is how to describe quantum correlations among ancillas induced by successive system-ancilla interactions. Another challenge is how to deal with initially correlated ancillas. Here we develop a tensor network formalism to address both challenges. We show that the induced correlations in the standard collision model are well captured by a matrix product state (a matrix product density operator) if the colliding particles are in pure (mixed) states. In the case of the initially correlated ancillas, we construct a general tensor diagram for the system dynamics and derive a memory-kernel master equation. Analyzing the perturbation series for the memory kernel, we go beyond the recent results concerning the leading role of two-point correlations and consider multipoint correlations (Waldenfelds cumulants) that become relevant in the higher-order stroboscopic limits. These results open an avenue for the further analysis of memory effects in collisional quantum dynamics.
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Wang Z, Bao Z, Wu Y, Li Y, Cai W, Wang W, Ma Y, Cai T, Han X, Wang J, Song Y, Sun L, Zhang H, Duan L. A flying Schrödinger's cat in multipartite entangled states. SCIENCE ADVANCES 2022; 8:eabn1778. [PMID: 35275710 PMCID: PMC8916730 DOI: 10.1126/sciadv.abn1778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/19/2022] [Indexed: 06/14/2023]
Abstract
Schrödinger's cat originates from the famous thought experiment querying the counterintuitive quantum superposition of macroscopic objects. As a natural extension, several "cats" (quasi-classical objects) can be prepared into coherent quantum superposition states, which is known as multipartite cat states demonstrating quantum entanglement among macroscopically distinct objects. Here, we present a highly scalable approach to deterministically create flying multipartite Schrödinger's cat states by reflecting coherent-state photons from a microwave cavity containing a superconducting qubit. We perform full quantum state tomography on the cat states with up to four photonic modes and confirm the existence of quantum entanglement among them. We also witness the hybrid entanglement between discrete-variable states (the qubit) and continuous-variable states (the flying multipartite cat) through a joint quantum state tomography. Our work provides an enabling step for implementing a series of quantum metrology and quantum information processing protocols based on cat states.
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Wei ZY, Malz D, Cirac JI. Sequential Generation of Projected Entangled-Pair States. PHYSICAL REVIEW LETTERS 2022; 128:010607. [PMID: 35061477 DOI: 10.1103/physrevlett.128.010607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/30/2021] [Accepted: 11/30/2021] [Indexed: 06/14/2023]
Abstract
We introduce plaquette projected entangled-pair states, a class of states in a lattice that can be generated by applying sequential unitaries acting on plaquettes of overlapping regions. They satisfy area-law entanglement, possess long-range correlations, and naturally generalize other relevant classes of tensor network states. We identify a subclass that can be more efficiently prepared in a radial fashion and that contains the family of isometric tensor network states [M. P. Zaletel and F. Pollmann, Phys. Rev. Lett. 124, 037201 (2020)PRLTAO0031-900710.1103/PhysRevLett.124.037201]. We also show how this subclass can be efficiently prepared using an array of photon sources.
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Affiliation(s)
- Zhi-Yuan Wei
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany and Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 München, Germany
| | - Daniel Malz
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany and Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 München, Germany
| | - J Ignacio Cirac
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany and Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 München, Germany
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Mohamed ABA, Eleuch H. Entanglement Dynamics Induced by a Squeezed Coherent Cavity Coupled Nonlinearly with a Qubit and Filled with a Kerr-Like Medium. ENTROPY 2021; 23:e23050496. [PMID: 33919469 PMCID: PMC8143461 DOI: 10.3390/e23050496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/18/2021] [Accepted: 04/19/2021] [Indexed: 11/16/2022]
Abstract
An analytical solution for a master equation describing the dynamics of a qubit interacting with a nonlinear Kerr-like cavity through intensity-dependent coupling is established. A superposition of squeezed coherent states is propped as the initial cavity field. The dynamics of the entangled qubit-cavity states are explored by negativity for different deformed function of the intensity-dependent coupling. We have examined the effects of the Kerr-like nonlinearity and the qubit-cavity detuning as well as the phase cavity damping on the generated entanglement. The intensity-dependent coupling increases the sensitivity of the generated entanglement to the phase-damping. The stability and the strength of the entanglement are controlled by the Kerr-like nonlinearity, the qubit-cavity detuning, and the initial cavity non-classicality. These physical parameters enhance the robustness of the qubit-cavity entanglement against the cavity phase-damping. The high initial cavity non-classicality enhances the robustness of the qubit-cavity entanglement against the phase-damping effect.
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Affiliation(s)
- Abdel-Baset A. Mohamed
- Department of Mathematics, College of Science and Humanities in Al-Aflaj, Prince Sattam Bin Abdulaziz University, Al-Aflaj 11942, Saudi Arabia
- Department of Mathematics, Faculty of Science, Assiut University, Assiut 71515, Egypt
- Correspondence:
| | - Hichem Eleuch
- Department of Applied Physics and Astronomy, University of Sharjah, Sharjah 27272, United Arab Emirates;
- Department of Applied Sciences and Mathematics, College of Arts and Sciences, Abu Dhabi University, Abu Dhabi 59911, United Arab Emirates
- Institute for Quantum Science and Engineering, Texas A&M University, College Station, TX 77843, USA
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