- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Quantum Dialogue Based on Entanglement Swapping and Hadamard Operation via Cavity QED
摘要： A quantum dialogue scheme based on entanglement swapping and Hadamard operation via cavity QED is proposed, which effectively uses the evolution law of atom in cavity QED. The proposed scheme uses Bell states and GHZ states as quantum resource and only needs single-atom measurements. The proposed scheme is secure against active attacks from an eavesdropper and can transmit 4 secret bits per round communication.
关键词： Entanglement swapping,Hadamard operation,Quantum dialogue,Cavity QED
更新于2025-09-23 15:23:52
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Vacuum-enhanced optical nonlinearities with disordered molecular photoswitches
摘要： It is well known that nonlinear optical signals such as cross-phase modulation can be coherently enhanced in multilevel atomic gases under conditions of electromagnetically induced transparency, but analogous results in solids are challenging to obtain due to natural energetic disorder. We propose a solid-state cavity QED scheme to enable cross-phase modulation between two arbitrarily weak classical fields in the optical domain, using a highly disordered intracavity medium composed of organic molecular photoswitches. Even in the presence of strong energetic and orientational disorder, the unique spectral properties of organic photoswitches can be used to enhance the desired nonlinearity under conditions of vacuum-induced transparency, enabling cross-phase modulation signals that surpass the detection limit imposed by absorption losses. Possible applications of the scheme include integrated all-optical switching with low photon numbers.
关键词： organic photoswitches,cavity QED,vacuum-induced transparency,cross-phase modulation,disorder
更新于2025-09-23 15:23:52
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Effect of the Diamagnetic term in the ultra-strong coupling regime
摘要： We consider a set of two level atoms interacting with a single quantized bosonic mode governed by the Dicke model. In this model it is well known that under a critical value of the light-matter coupling a spontaneous radiation process takes place. In the present work, we investigate the dynamics of the system and we study the Wigner distribution function to visualize the effect of the minimal coupling on the ground state wavefunction from the normal phase to the superradiant one. We show also that the entanglement of Bi-partite model is limited by the presence of the diamagnetic term.
关键词： diamagnetic term,Circuit QED,Cavity QED,Entanglement
更新于2025-09-23 15:22:29
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An efficient quantum photonic phase shift in a low Q-factor regime
摘要： Solid-state quantum emitters have long been recognised as the ideal platform to realize integrated quantum photonic technologies. We demonstrate that a self-assembled negatively charged quantum dot (QD) in a low Q-factor photonic micropillar is a suitable design for deterministic polarisation switching and spin-photon entanglement. We show this by measuring a shift in phase of an input single photon of at least 2π/3. As we explain in the text, this is strong experimental proof that input photons can interact with the emitter deterministically. A deterministic photon-emitter interaction is a viable and scalable means to achieve several vital functionalities such as single photon switches and entanglement gates. Our experimentally determined value is limited by mode mismatch between the input laser and the cavity, QD spectral fluctuations and spin relaxation. When on-resonance we estimate that up to ～ 80% of the collected photons couple into the cavity mode and have interacted with the QD and undergone a phase shift of π.
关键词： micropillar cavity,quantum dot,cavity QED
更新于2025-09-23 15:22:29
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Collective excitations and supersolid behavior of bosonic atoms inside two crossed optical cavities
摘要： We discuss the nature of symmetry breaking and the associated collective excitations for a system of bosons coupled to the electromagnetic field of two optical cavities. For the specific configuration realized in a recent experiment at ETH [1, 2], we show that, in absence of direct intercavity scattering and for parameters chosen such that the atoms couple symmetrically to both cavities, the system possesses an approximate U(1) symmetry which holds asymptotically for vanishing cavity field intensity. It corresponds to the invariance with respect to redistributing the total intensity = + I 2 between the two cavities. The spontaneous breaking of this symmetry gives rise to a broken continuous translation-invariance for the atoms, creating a supersolid-like order in the presence of a Bose–Einstein condensate. In particular, we show that atom-mediated scattering between the two cavities, which favors the state with equal light intensities =I 2, gives 1 rise to a finite value ~ I of the effective Goldstone mass. For strong atom driving, this low energy mode is clearly separated from an effective Higgs excitation associated with changes of the total intensity I. In addition, we compute the spectral distribution of the cavity light field and show that both the Higgs and Goldstone mode acquire a finite lifetime due to Landau damping at non-zero temperature.
关键词： superradiance,ultracold atoms,self-ordering,symmetry breaking,supersolidity,cavity QED,Goldstone mode
更新于2025-09-23 15:21:01
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Theory of valley-resolved spectroscopy of a Si triple quantum dot coupled to a microwave resonator
摘要： We theoretically study a silicon triple quantum dot (TQD) system coupled to a superconducting microwave resonator. The response signal of an injected probe signal can be used to extract information about the level structure by measuring the transmission and phase shift of the output field. This information can further be used to gain knowledge about the valley splittings and valley phases in the individual dots. Since relevant valley states are typically split by several μeV, a finite temperature or an applied external bias voltage is required to populate energetically excited states. The theoretical methods in this paper include a capacitor model to fit experimental charging energies, an extended Hubbard model to describe the tunneling dynamics, a rate equation model to find the occupation probabilities, and an input–output model to determine the response signal of the resonator.
关键词： quantum dots,hybrid quantum systems,spin qubits,valley,silicon,cavity QED
更新于2025-09-23 15:19:57
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Realization of Nonlinear Optical Nonreciprocity on a Few-Photon Level Based on Atoms Strongly Coupled to an Asymmetric Cavity
摘要： Optical nonreciprocity is important in photonic information processing to route the optical signal or prevent the reverse flow of noise. By adopting the strong nonlinearity associated with a few atoms in a strongly coupled cavity QED system and an asymmetric cavity configuration, we experimentally demonstrate the nonreciprocal transmission between two counterpropagating light fields with extremely low power. The transmission of 18% is achieved for the forward light field, and the maximum blocking ratio for the reverse light is 30 dB. Though the transmission of the forward light can be maximized by optimizing the impedance matching of the cavity, it is ultimately limited by the inherent loss of the scheme. This nonreciprocity can even occur on a few-photon level due to the high optical nonlinearity of the system. The working power can be flexibly tuned by changing the effective number of atoms strongly coupled to the cavity. The idea and result can be applied to optical chips as optical diodes by using fiber-based cavity QED systems. Our work opens up new perspectives for realizing optical nonreciprocity on a few-photon level based on the nonlinearities of atoms strongly coupled to an optical cavity.
关键词： optical nonreciprocity,few-photon level,asymmetric cavity,nonlinear optics,cavity QED
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
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A Realization of a Quasi-Random Walk for Atoms in Time-Dependent Optical Potentials
摘要： We consider the time dependent dynamics of an atom in a two-color pumped cavity, longitudinally through a side mirror and transversally via direct driving of the atomic dipole. The beating of the two driving frequencies leads to a time dependent effective optical potential that forces the atom into a non-trivial motion, strongly resembling a discrete random walk behavior between lattice sites. We provide both numerical and analytical analysis of such a quasi-random walk behavior.
关键词： optomechanics,cavity QED,random motion
更新于2025-09-09 09:28:46
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Scattering characteristics of an exciton-plasmon nanohybrid made by coupling a monolayer graphene nanoflake to a carbon nanotube
摘要： A hybrid nanostructure where a graphene nanoflake (GNF) is optically coupled to a carbon nanotube (CNT) could potentially possess enhanced sensing capabilities compared to the individual constituents whilst inheriting their high biocompatibility, favourable electrical, mechanical and spectroscopic properties. Therefore, in this paper, we investigate the scattering characteristics of an all-carbon exciton-plasmon nanohybrid which was made by coupling an elliptical GNF resonator to a semiconducting CNT gain element. We analytically model the nanohybrid as an open quantum system using cavity quantum electrodynamics. We derive analytical expressions for the dipole moment operator and the dipole response field of the GNF and characterize the Rayleigh scattering spectrum of the nanohybrid. These analytical expressions are valid for any arbitrary ellipsoidal nanoresonator coupled to a quantum emitter. Furthermore, we perform a detailed numerical analysis, the results of which indicate that the GNF-CNT nanohybrid exhibits enhanced and versatile scattering capabilities compared to the individual constituents. We show that the spectral signatures of the nanohybrid are highly tunable using a multitude of system parameters such as Fermi energy of the GNF, component dimensions, GNF-CNT separation distance and the permittivity of the submerging medium. We finally demonstrate the prospect of using the proposed nanohybrid to reconstruct the permittivity profile of a tumour. The high biocompatibility and high sensitivity to the dielectric properties of the environment make the proposed GNF-CNT nanohybrid an ideal candidate for such biosensing applications.
关键词： cavity QED analysis,scattering,nanoplasmonics
更新于2025-09-09 09:28:46