27 research outputs found
Quantum metrology enhanced by the spin interaction in a generalized Tavis-Cummings model
Quantum metrology is recognized for its capability to offer high-precision
estimation by utilizing quantum resources, such as quantum entanglement. Here,
we propose a generalized Tavis-Cummings model by introducing the spin
interaction to explore the impact of the many-body effect on estimation
precision, quantified by the quantum Fisher information (QFI). By deriving the
effective description of our model, we establish a closed relationship between
the QFI and the spin fluctuation induced by the spin interaction. Based on
this exact relation, we emphasize the indispensable role of the spin anisotropy
in achieving the Heisenberg-scaling precision for estimating a weak magnetic
field. Furthermore, we observe that the estimation precision can be enhanced by
increasing the strength of the spin anisotropy. We also reveal a clear scaling
transition of the QFI in the Tavis-Cummings model with the reduced Ising
interaction. Our results contribute to the enrichment of metrology theory by
considering many-body effects, and they also present an alternative approach to
improving the estimation precision by harnessing the power provided by
many-body quantum phases
Tripartite quantum entanglement with squeezed optomechanics
The ability to engineer entangled states that involve macroscopic objects is
of particular importance for a wide variety of quantum-enabled technologies,
ranging from quantum information processing to quantum sensing. Here we propose
how to achieve coherent manipulation and enhancement of quantum entanglement in
a hybrid optomechanical system, which consists of a Fabry-P\'{e}rot cavity with
two movable mirrors, an optical parametric amplifier (OPA), and an injected
squeezed vacuum reservoir. We show that the advantages of this system are
twofold: (i) one can effectively regulate the light-mirror interactions by
introducing a squeezed intracavity mode via the OPA; (ii) when properly
matching the squeezing parameters between the squeezed cavity mode and the
injected squeezed vacuum reservoir, the optical input noises can be suppressed
completely. These peculiar features of this system allow us to generate and
manipulate quantum entanglement in a coherent and controllable way. More
importantly, we also find that such controllable entanglement, under some
specific squeezing parameters, can be considerably enhanced in comparison with
those of the conventional optomechanical system. Our work, providing a
promising method to regulate and tailor the light-mirror interaction, are
poised to serve as a useful tool for engineering various quantum effects which
are based on cavity optomechanics.Comment: 11 pages, 3 figure
The surgical strategy for eosinophilic granuloma of the pediatric cervical spine complicated with neurologic deficit and/or spinal instability
Aridity trend and response to vegetation restoration in the loess hilly region of northern Shaanxi Province
Antibunching Effects in the Hybrid Cavity–Bose–Einstein Condensates System
We theoretically study the model of a hybrid cavity–Bose–Einstein condensates (BEC) system that consists of a two-level impurity atom coupled to a cavity–BEC system with radiation pressure coupling, where the system is weakly driven by a monochromatic laser field. The steady-states behavior of the entire system is researched in the framework of the impurity–cavity coupling dispersive limit. We find that the multiple types of photon steady-state antibunching effects can be obtained when only the dissipation of the cavity is included. Moreover, the strength and frequency range of conventional steady-state antibunching effects of the cavity can be significantly modified by the impurity atom and intrinsic non-linearity of BEC. This result shows that our study can provide a method to tune the antibunching effects of the cavity field. In addition, the non-standard photon blockade or superbunching effect with the suppression of two-photon correlation and enhancement of three-photon correlation can be realized. The frequency range of the superbunching effect also can be changed by the impurity atom and intrinsic non-linearity of BEC. Therefore, our study shows many quantum statistical characteristics in a hybrid cavity–BEC quantum system and its manipulation
Transient and Fast Generation of Bose-Einstein-Condensate Macroscopic Quantum Superposition States via Impurity Catalysing
Macroscopic quantum superposition is an important embodiment of the core of the quantum theory. The engineering of macroscopic quantum superposition states is the key to quantum communication and quantum computation. Thus, we present a theoretical proposal to engineer macroscopic quantum superposition (MQS) states of a Bose-Einstein condensate (BEC) via impurity atoms. We firstly propose a deterministic generation scheme of transient multi-component MQS states of the BEC via impurity catalysing. It is found that the structure of the generated transient multi-component MQS states can be manipulated by the impurity number parity. Then, we illustrate the influence of impurity number parity on MQS states through three aspects: generation of approximately orthogonal continuous-variable cat states, manipulation of non-classicality in phase space, and switching of non-classical degree of BEC states. The influence of the BEC decoherence on the generation of MQS states is discussed by the fidelity between actually generated states and target states. Finally, the results show that the high-fidelity multi-component MQS states of the BEC can be fast generated by increasing the coherent interaction strength between impurities and the BEC in an open system
Antibunching Effects in the Hybrid Cavity–Bose–Einstein Condensates System
We theoretically study the model of a hybrid cavity–Bose–Einstein condensates (BEC) system that consists of a two-level impurity atom coupled to a cavity–BEC system with radiation pressure coupling, where the system is weakly driven by a monochromatic laser field. The steady-states behavior of the entire system is researched in the framework of the impurity–cavity coupling dispersive limit. We find that the multiple types of photon steady-state antibunching effects can be obtained when only the dissipation of the cavity is included. Moreover, the strength and frequency range of conventional steady-state antibunching effects of the cavity can be significantly modified by the impurity atom and intrinsic non-linearity of BEC. This result shows that our study can provide a method to tune the antibunching effects of the cavity field. In addition, the non-standard photon blockade or superbunching effect with the suppression of two-photon correlation and enhancement of three-photon correlation can be realized. The frequency range of the superbunching effect also can be changed by the impurity atom and intrinsic non-linearity of BEC. Therefore, our study shows many quantum statistical characteristics in a hybrid cavity–BEC quantum system and its manipulation
Measuring the <i>p</i>th-Order Correlation Function of Light Field via Two-Level Atoms
In this paper, we present a method for measuring arbitrary-order correlation functions of the light field using a two-level atomic system. Theoretically, light field information should be mapped onto the atomic system after the light interacts with the atom. Therefore, we can measure the atomic system and thus obtain information about the light field. We study two typical models, the p-photon Jaynes–Cummings model, and the p-photon Tavis–Cummings model. In both models, we find that the pth-order correlation function of an unknown light field can be obtained by measuring the instantaneous change of energy of the two-level atoms with the aid of a known reference light field. Moreover, we find that the interactions other than the dipole interactions between light and atoms have no effect on the measurement results
The Evaluation on Corrosion Resistance and Dross Formation of Zn–23 wt% Al–0.3 wt% Si–x wt% Mg Alloy
: A comparative study of the corrosive resistance and dross formation of 55Al–Zn–1.6Si (wt%) (55AZS) and 23Al–Zn–0.3Si–xMg (wt%) (23AZS–xMg, x = 0, 1.5, 3) alloys are performed using immersion corrosion and dross formation test, respectively. The result of immersion corrosion testing shows that corrosive rate of the 23AZS alloy is lower than that of 55AZS alloy in the latter stage of immersion and 23AZS–1.5Mg alloy shows the optimal corrosive resistance compared to other alloys relatively. The result of dross formation test shows that the number of bottom dross particle formed in 23AZS–xMg (x = 0, 1.5, 3) alloy is less than that in 55AZS alloy. Moreover, the thermodynamic calculation is performed to reveal the solubility of Fe in the alloys, the result shows the solubility of Fe reduces as a decrease of Al content in the alloy, and the number of dross particle (Fe4Al13 and 6 (Al9Fe2Si2) phase) generated in 23AZS alloy is more than that in 55AZS alloy. In general, 23AZS–1.5Mg alloy has an advantage of less dross and a certain corrosion resistance and it is expected to be applied for the hot stamping process of coating
One-shot coherence distillation in superconducting circuit systems
Distilling quantum coherence is important for optimizing the performance of quantum technologies, however, it cannot always be accomplished with certainty. Then, the probabilistic distillation of quantum coherence has been developed and successfully implemented in experiments. We introduce a proposal to realize the one-shot coherence distillation in the superconducting circuit system. The target maximally coherent state can be extracted from a single copy of the prepared state by using appropriate incoherent operations and a finite error tolerance is allowed. It is easy to implement our scheme in the experiment that only a superconducting qubit is required to be the auxiliary system. To demonstrate the feasibility of our scheme, we numerically simulate the distillation process under the influence of dephasing (according to the typical experimental parameters). We find that the distillation rate of the coherence resource can be well achieved with the current experimental technique