Influence of Indefinite Causal Order on Otto Heat Engine

Quantum effect plays important roles in quantum thermodynamics, and recently the application of indefinite causal order to quantum thermodynamics has attracted much attentions. Based on two trapped ions, we propose a scheme to add an indefinite causal order to the isochoric cooling stroke of Otto engine through reservoir engineering. Then, we observe that the quasi-static efficiency of this heat engine is far beyond the efficiency of a normal Otto heat engine and may reach 1. When the power is its maximum, the efficiency is also much higher than that of a normal Otto heat engine. This enhancement may origin from the non-equilibrium of reservoir and the measurement on control qubit.

Central potential effects induced by Lorentz symmetry violation on modified quantum oscillator field

In this paper, effects of Lorentz symmetry violation determined by a tensor field [Formula: see text] out of the Standard Model Extension on a modified quantum oscillator field in the presence of Cornell-type scalar potential are analyzed. We first introduced a scalar potential [Formula: see text] by modifying the mass square term via transformation [Formula: see text] in the Klein–Gordon equation, and then replace the momentum operator [Formula: see text], where [Formula: see text] is an arbitrary function other than [Formula: see text] to study the modified Klein–Gordon oscillator. We solve the wave equation and obtain the analytical bound-states solutions and see the dependence of oscillator frequency [Formula: see text] on the quantum numbers [Formula: see text] as well as on Lorentz-violating parameters with the potential which shows a quantum effect.

Dynamical Casimir–Polder force in a semi-infinite rectangle waveguide

In this paper, we study the dynamical Casimir–Polder force between an ensemble of identical two-level atoms and the wall of a rectangle waveguide with semi-infinite length. With the presence of both the rotating wave and counter rotating wave terms in the light–matter interaction Hamiltonian, we utilize the perturbation theory to solve the Heisenberg equation. Up to the seconder of coupling strength, we obtain the energy shift analytically and the Casimir–Polder force numerically. Our result shows that the dynamical behavior of the Casimir force is closely connected to the photon propagation in the waveguide. Therefore, we hope this work will stimulate the studies about the quantum effect in waveguide scenario.

Flexoelectricity Driven Fano Resonance in Slotted Carbon Nanotubes for Decoupled Multifunctional Sensing

Multifunctionality, interference-free signal readout, and quantum effect are important considerations for flexible sensors equipped within a single unit towards further miniaturization. To address these criteria, we present the slotted carbon nanotube (CNT) junction features tunable Fano resonance driven by flexoelectricity, which could serve as an ideal multimodal sensory receptor. Based on extensive ab initio calculations, we find that the effective Fano factor can be used as a temperature-insensitive extrinsic variable for sensing the bending strain, and the Seebeck coefficient can be used as a strain-insensitive intrinsic variable for detecting temperature. Thus, this dual-parameter permits simultaneous sensing of temperature and strain without signal interference. We further demonstrate the applicability of this slotted junction to ultrasensitive chemical sensing which enables precise determination of donor-type, acceptor-type, and inert molecules. This is due to the enhancement or counterbalance between flexoelectric and chemical gating. Flexoelectric gating would preserve the electron–hole symmetry of the slotted junction whereas chemical gating would break it. As a proof-of-concept demonstration, the slotted CNT junction provides an excellent quantum platform for the development of multistimuli sensation in artificial intelligence at the molecular scale.

Extraordinary optical transmission from a thin microcavity by macroscopic quantum effect

The macroscopic quantum effect is revealed to elaborate the extraordinary optical transmission (EOT) from a subwavelength thin microcavity based on the uncertainty property of the transmitted electromagnetic fields after the aperture. A critical radius is found in the thin microcavity under a certain incident electromagnetic wavelength. With the aperture radius varying, the transmitted field can be divided into three regimes: I. the macroscopic quantum regime when the aperture radius is less than the critical radius, in which the field edge effect occurs and EOT phenomenon is perfectly manifested; II. The wave-particle duality regime in the vicinity of the critical radius, in which the edge effect and diffraction phenomenon exist simultaneously; III. The wave regime when the aperture radius is greater than the critical radius, in which the near-field diffraction emerges. In addition, the influences of incident wavelength and microcavity thickness on EOT are also investigated. Our research have potential applications in advanced optical devices, such as light switch and optical manipulations.

Quantum mechanical investigation of N+N2 collision: state-to-state non-reaction and exchange reaction probabilities and rate constants

We present a state-to-state dynamical calculation on the exchange reaction N+N2→N2+N and the non-reaction N+N2→N+N2 based on the potential energy surface published by Mankodi et al. The calculation is performed using the time-independent quantum reaction scattering program. The reactivity of both reaction processes is discussed by reaction properties of vibrational quantum numbers v=0-3 and rotational quantum numbers j=0-32 (such as cumulative reaction probability, state-to-state reaction probabilities, and cross sections of N exchange, state-to-state rate constants for both reactions). The threshold energy of the exchange reaction can decrease with the decrease of vibrational excitation or the increase of rotational excitation. By using the J-shifting approximation, rate constants are reported for both reactions. The comparison of the presented total rate constant of the N+N2 exchange reaction with the previous results shows that the quantum effect is not negligible at low temperatures. For the exchange reaction, the rate constant at 500K decreases by about 10 orders of magnitude when the vibrational level of N2 increases from 0 to 7, indicating that the rate constants are sensitive to the initial vibrational level of N2 at low temperatures. For non-reactive collisions, the rate constants have little effect on the initial ro-vibrational levels of N2 at low temperatures.

Quantum Entanglement in Time

<p>This thesis is in the field of quantum information science, which is an area that reconceptualizes quantum physics in terms of information. Central to this area is the quantum effect of entanglement in space. It is an interdependence among two or more spatially separated quantum systems that would be impossible to replicate by classical systems. Alternatively, an entanglement in space can also be viewed as a resource in quantum information in that it allows the ability to perform information tasks that would be impossible or very difficult to do with only classical information. Two such astonishing applications are quantum communications which can be harnessed for teleportation, and quantum computers which can drastically outperform the best classical supercomputers. In this thesis our focus is on the theoretical aspect of the field, and we provide one of the first expositions on an analogous quantum effect known as entanglement in time. It can be viewed as an interdependence of quantum systems across time, which is stronger than could ever exist between classical systems. We explore this temporal effect within the study of quantum information and its foundations as well as through relativistic quantum information. An original contribution of this thesis is the design of one of the first quantum information applications of entanglement in time, namely a quantum blockchain. We describe how the entanglement in time provides the quantum advantage over a classical blockchain. Furthermore, the information encoding procedure of this quantum blockchain can be interpreted as non-classically influencing the past, and hence the system can be viewed as a `quantum time machine.'</p>

Quantum mechanical solution to spectral lineshape in strongly-coupled atomnanocavity system

The strongly coupled system composed of atoms, molecules, molecule aggregates, and semiconductor quantum dots embedded within an optical microcavity/nanocavity with high quality factor and/or low modal volume has become an excellent platform to study cavity quantum electrodynamics (CQED), where a prominent quantum effect called Rabi splitting can occur due to strong interaction of cavity-mode single-photon with the two-level atomic states. In this paper, we build a new quantum model that can describe the optical response of the strongly-coupled system under the action of an external probing light and the spectral lineshape. We take the Hamiltonian for the strongly-coupled photon-atom system as the unperturbed Hamiltonian H 0 and the interaction Hamiltonian of the probe light upon the coupled-system quantum states as the perturbed Hamiltonian V. The theory yields a double Lorentzian lineshape for the permittivity function, which agrees well with experimental observation of Rabi splitting in terms of spectral splitting. This quantum theory will pave the way to construct a complete understanding for the microscopic strongly-coupled system that will become an important element for quantum information processing, nano-optical integrated circuits, and polariton chemistry.

Quantum Entanglement in Time

<p>This thesis is in the field of quantum information science, which is an area that reconceptualizes quantum physics in terms of information. Central to this area is the quantum effect of entanglement in space. It is an interdependence among two or more spatially separated quantum systems that would be impossible to replicate by classical systems. Alternatively, an entanglement in space can also be viewed as a resource in quantum information in that it allows the ability to perform information tasks that would be impossible or very difficult to do with only classical information. Two such astonishing applications are quantum communications which can be harnessed for teleportation, and quantum computers which can drastically outperform the best classical supercomputers. In this thesis our focus is on the theoretical aspect of the field, and we provide one of the first expositions on an analogous quantum effect known as entanglement in time. It can be viewed as an interdependence of quantum systems across time, which is stronger than could ever exist between classical systems. We explore this temporal effect within the study of quantum information and its foundations as well as through relativistic quantum information. An original contribution of this thesis is the design of one of the first quantum information applications of entanglement in time, namely a quantum blockchain. We describe how the entanglement in time provides the quantum advantage over a classical blockchain. Furthermore, the information encoding procedure of this quantum blockchain can be interpreted as non-classically influencing the past, and hence the system can be viewed as a `quantum time machine.'</p>