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- 实验方案
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Generation of single entangled photon-phonon pairs via an atom-photon-phonon interaction
摘要： Antibunching and entanglement play important roles in quantum information processing as antibunching is an essential ingredient for the production of single photons (phonons) and entanglement is a crucial resource for quantum communication and metrology. In this paper, we propose a atom-photon-phonon (tripartite) interaction in a hybrid cavity-atom-mechanics system, and show that both photon and phonon antibunching can be observed simultaneously under the resonant atomic driving. More importantly, the generated single photons and phonons are strongly correlated and entangled with each other, i.e., single entangled photon-phonon pairs are generated via the atom-photon-phonon interaction. The generation of single entangled photon-phonon pairs is the first step to implement entanglement-based quantum state transfer, which is essential for connecting mechanical and optical systems to build hybrid quantum networks.
关键词： antibunching,entanglement,atom-photon-phonon interaction,quantum information processing,hybrid cavity-atom-mechanics system
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Universal Multipartite D-Level Entanglement Witnesses for Realistic Measurement Settings
摘要： Entanglement is an essential resource in quantum information science [1] and its presence in any quantum system can be experimentally detected through entanglement witness operators [2]. In particular, measuring a negative expectation value of a witness with high statistical confidence provides a necessary and sufficient condition to confirm the generation of a genuine multipartite [3] and/or d-level entangled state [4]. In recent years, the experimental generation of complex quantum states has intensified the need for witnesses that are capable of detecting such systems and are experimentally optimal at the same time. This means that the witness should require the least measurement effort (in terms of number and complexity of the measurement settings), include only projections on single qudits, while at the same time possessing a high noise tolerance (Fig. 1a). However, “experimentally-friendly” witnesses capable of accomplishing these tasks have not been derived yet. Here, we provide a universal method to construct experimentally-optimal witnesses capable of detecting entanglement in any arbitrarily-complex quantum state that can be customized towards experimental restrictions and/or accessible measurement settings [5]. As an example, using our technique and exploiting the stabilizer formalism [6,7], we derive an entanglement witness for N-partite d-level cluster states that consists of only two measurement settings. We apply our method to experimentally measure the expectation value of a witness for a four-partite three-level optical cluster states [8]. Through projection measurements in an optical time/frequency photon system [9-10], we measured a witness expectation value -0.28±0.04<0 (Fig.1b), thus confirming the realization of genuine four-partite cluster state entanglement. Finally, we used the derived witness to investigate the white noise tolerance of multipartite d-level cluster states and demonstrate that this increases with the number of level. Our approach is completely universal and can be applied to any complex quantum state.
关键词： entanglement witnesses,multipartite d-level entanglement,entanglement,measurement settings,quantum information
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Seoul, Korea (South) (2019.1.27-2019.1.31)] 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - High-Frequency Hexagonal Boron Nitride (h-BN) Phononic Waveguides
摘要： This digest paper presents the first experimental demonstration of nanoscale phononic waveguides based on a two-dimensional (2D) layered crystalline material, namely hexagonal boron nitride (h-BN). Taking advantage of the planar geometry, the challenges in nanofabrication of 2D materials can be circumvented through a heterogeneous integration approach. Rich wave propagation characteristics of h-BN phononic waveguides are revealed in both finite element method (FEM) simulations and transmission measurements. Numerical analysis further indicates that the frequency response of the designed h-BN phononic waveguides can be finely tuned by varying the thickness or tension level of the h-BN crystals, across the high frequency (HF, 3?30 MHz) to very high frequency (VHF, 30?300 MHz) bands. Manipulation and guiding of high frequency mechanical waves on integratable 2D device platforms will open new opportunities in radio-frequency (RF) signal processing and on-chip quantum information technologies.
关键词： phononic waveguides,very high frequency (VHF),radio-frequency (RF) signal processing,quantum information technologies,high frequency (HF),hexagonal boron nitride (h-BN)
更新于2025-09-12 10:27:22
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Teleportation of two-qubit entangled state via non-maximally entangled GHZ state
摘要： Quantum teleportation is of significant meaning in quantum information. We study the probabilistic teleportation of unknown two-qubit entangled state utilizing non-maximally entangled GHZ state as quantum channel. We formulate it as unambiguous state discrimination problem and derive exact optimal POVM operator for maximizing the success probability of unambiguous state discrimination. Only one three-qubit POVM for the sender, one two-qubit unitary operation for the receiver and two cbits for outcome notification are required in this scheme. The unitary operation is given in the form of concise formula and average fidelity is calculated. We show that our scheme is applicable in the situation where the information of quantum channel is only available for the sender.
关键词： Probabilistic teleportation,Optimal POVM,Quantum information theory,Unambiguous state discrimination
更新于2025-09-12 10:27:22
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Tunable Quantum Beat of Single Photons Enabled by Nonlinear Nanophotonics
摘要： We demonstrate the tunable quantum beat of single photons through the co-development of core nonlinear nanophotonic technologies for frequency-domain manipulation of quantum states in a common physical platform. Spontaneous four-wave mixing in a nonlinear resonator is used to produce nondegenerate, quantum-correlated photon pairs. One photon from each pair is then frequency shifted, without degradation of photon statistics, using four-wave-mixing Bragg scattering in a second nonlinear resonator. Fine tuning of the applied frequency shift enables tunable quantum interference of the two photons as they are impinged on a beam splitter, with an oscillating signature that depends on their frequency difference. Our work showcases the potential of nonlinear nanophotonic devices as a valuable resource for photonic quantum-information science.
关键词： four-wave-mixing Bragg scattering,nonlinear nanophotonics,frequency-domain manipulation,quantum interference,quantum states,quantum beat,single photons,photonic quantum-information science,quantum-correlated photon pairs,spontaneous four-wave mixing
更新于2025-09-11 14:15:04
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Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots
摘要： Detailed theoretical studies of the electronic structure of (InGa)(AsSb)/GaAs/GaP quantum dots are presented. This system is unique since it exhibits concurrently direct and indirect transitions both in real and momentum space and is attractive for applications in quantum information technology, showing advantages as compared to the widely studied (In,Ga)As/GaAs dots. We proceed from the inspection of the con?nement potentials for k (cid:2)= 0 and k = 0 conduction and k = 0 valence bands, through the formulation of k · p calculations for k-indirect transitions, up to the excitonic structure of (cid:2) transitions. Throughout this process we compare the results obtained for dots on both GaP and GaAs substrates, enabling us to make a direct comparison to the (In,Ga)As/GaAs quantum dot system. We also discuss the realization of quantum gates.
关键词： excitonic structure,quantum dots,electronic structure,quantum gates,quantum information technology
更新于2025-09-11 14:15:04
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Coherent transfer of quantum information in a silicon double quantum dot using resonant SWAP gates
摘要： Spin-based quantum processors in silicon quantum dots offer high-fidelity single and two-qubit operation. Recently multi-qubit devices have been realized; however, many-qubit demonstrations remain elusive, partly due to the limited qubit-to-qubit connectivity. These problems can be overcome by using SWAP gates, which are challenging to implement in devices having large magnetic field gradients. Here we use a primitive SWAP gate to transfer spin eigenstates in 100 ns with a fidelity of F(p)SWAP = 98%. By swapping eigenstates we are able to demonstrate a technique for reading out and initializing the state of a double quantum dot without shuttling charges through the quantum dot. We then show that the SWAP gate can transfer arbitrary two-qubit product states in 300 ns with a fidelity of F(c)SWAP = 84%. This work sets the stage for many-qubit experiments in silicon quantum dots.
关键词： silicon quantum dots,quantum processors,SWAP gates,spin eigenstates,quantum information
更新于2025-09-11 14:15:04
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Effects of interface steps on the valley-orbit coupling in a Si/SiGe quantum dot
摘要： Valley-orbit coupling is a key parameter for a silicon quantum dot in determining its suitability for applications in quantum information processing. In this paper we study the effect of interface steps on the magnitude and phase of valley-orbit coupling for an electron in a silicon quantum dot. Within the effective-mass approximation, we ?nd that the location of a step on the interface is important in determining both the magnitude and the phase of the valley-orbit coupling in a Si/SiGe quantum dot. Speci?cally, our numerical results show that the magnitude of valley-orbit coupling can be suppressed up to 75% by a step of one atomic monolayer, and its phase can change by almost π . When two steps are present, the minimum value of the valley-orbit coupling can even approach zero. Our calculation can in principle be generalized to multiple steps as well, as long as the width of the regions between steps is much larger than the atomistic length scale. We also clarify the effects of an applied external magnetic ?eld and the higher orbital states on the valley-orbit coupling. Overall, our results illustrate that interface roughness can strongly affect both the magnitude and the phase of the valley-orbit coupling, which are crucial parameters for both spin and charge qubits in silicon.
关键词： interface steps,silicon quantum dot,effective-mass approximation,quantum information processing,valley-orbit coupling
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - 8×8 Programmable Si <sub/>3</sub> N <sub/>4</sub> Photonic Processor for Linear Quantum Processing
摘要： Universal linear optical networks made of on-chip tunable beam splitters and phase shifters form a very promising platform for quantum information processing (QIP). Thanks to their phase stability and reconfigurability, they are robust and enable a variety of quantum information and communication protocols such as quantum teleportation, quantum key distribution, photonic qubit gate protocols and boson sampling. We introduce an 8×8 mode Blass matrix as universal transformation circuit for linear-optical quantum information processing implemented on stoichiometric Si3N4 waveguides. The Si3N4 platform offers the unique combination of high index contrast, ultralow straight-propagation loss and a spectrally wide transparency range. In order to demonstrate that the photonic chip works as a linear-optical processor suited for general-purpose quantum information processing, we program on-chip quantum interference on several beam splitters within the Blass matrix and demonstrate a high visibility interference, obtaining an average fidelity of ~95%. To further demonstrate the flexibility and configurability of our processor we realized an 8-dimensional unitary transformation with single photons in an 8 dimensional rail encoding. Our findings demonstrate the suitability and reliability of a low-loss, integrated linear optical photonic processor based on Si3N4 waveguides. These results show the high potential of Si3N4 for the development of large universal linear optical quantum circuits, which is essential for the progress of quantum information processing.
关键词： Si3N4 waveguides,Blass matrix,linear optical networks,quantum information processing,quantum interference
更新于2025-09-11 14:15:04
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Quantum photonic transistor controlled by an atom in a Floquet cavity-QED system
摘要： The photon transmission of a Floquet cavity quantum electrodynamic (QED) system containing three periodically modulated cavities interacting with a two-level atom is investigated. The input-output relations and the second-order correlation functions of the output fields are calculated. The system demonstrates the feature of a quantum photonic transistor, i.e., the photon transmission is controlled by the quantum states of the atom. This device can be used as a building block for various quantum information processing.
关键词： photon transmission,Quantum photonic transistor,Floquet cavity-QED system,quantum information processing
更新于2025-09-11 14:15:04