Possibility of the tunneling time determination

On energy transfer by detection of a tunneling atom

We are in the process of building an experiment to study the tunneling of laser-cooled Rubidium atoms through an optical barrier. A particularly thorny set of questions arises when one considers the possibility of observing a tunneling particle while it is in the ``forbidden'' region. In earlier work, we have discussed how one might probe a tunneling atom ``weakly,'' so as to prevent collapse. Here we make some observations about the implications of a more traditional quantum measurement. Considerations of energy conservation suggest that attempts to observe tunneling atoms will enhance inelas…

Consistent analytical solution of the time-dependent Schrödinger equation for nanoscale circuits with laser-assisted quantum tunneling

It is now common practice to solve the Schrödinger equation to estimate the tunneling current between two metal electrodes at specified potentials, or the transmission through a potential barrier by assuming an incident, reflected, and transmitted wave. However, we suggest that these methods may not be appropriate for nanoscale circuits. The electron man-free path may be as long as 68.2 nm in metallic elements so we consider the possibility that quantum effects may occur throughout a nanoscale circuit, including the connections. Analytical methods are presented for modeling the coherent transf…

Relativistic Tunneling Through Two Successive Barriers

We study the relativistic quantum mechanical problem of a Dirac particle tunneling through two successive electrostatic barriers. Our aim is to study the emergence of the so-called \emph{Generalized Hartman Effect}, an effect observed in the context of nonrelativistic tunneling as well as in its electromagnetic counterparts, and which is often associated with the possibility of superluminal velocities in the tunneling process. We discuss the behavior of both the phase (or group) tunneling time and the dwell time, and show that in the limit of opaque barriers the relativistic theory also allows…

Experimental simulation of quantum tunneling in small systems

It is well known that quantum computers are superior to classical computers in efficiently simulating quantum systems. Here we report the first experimental simulation of quantum tunneling through potential barriers, a widespread phenomenon of a unique quantum nature, via NMR techniques. Our experiment is based on a digital particle simulation algorithm and requires very few spin-1/2 nuclei without the need of ancillary qubits. The occurrence of quantum tunneling through a barrier, together with the oscillation of the state in potential wells, are clearly observed through the experimental resu…

How to understand the tunneling in attosecond experiment?

The measurement of the tunneling time (T-time) in today's attosecond and strong field (low-frequency) experiments, despite its controversial discussion, offers a fruitful opportunity to understand time measurement and the time in quantum mechanics. In addition, as we will see in this work, a related controversial issue is the particulate nature of the radiation. Different models used to calculate the T-time will be discussed in this work in relation to my model of real T-time, Phys. Rev. {\bf 92}, 052118 (2015), where an intriguing similarity to the Bohr-Einstein photon box Gedanken experiment…

Quantum Tunneling and Caustics under Inverse Square Potential

Quantization of a harmonic oscillator with inverse square potential $V(x)=(m{ω^2}/2){x^2}+g/{x^2}$ on the line $-\infty<x<\infty$ is re-examined. It is shown that, for $0<g<3{\hbar^2}/(8m)$, the system admits a U(2) family of inequivalent quantizations allowing for quantum tunneling through the potenatial barrier at $x=0$. In the family is a distinguished quantization which reduces smoothly to the harmonic oscillator as $g\to 0$, in contrast to the conventional quantization applied to the Calogero model which prohibits the tunneling and has no such limit. The tunneling renders the classical ca…

Coherent Tunneling Adiabatic Passage with the Alternating Coupling Scheme

The use of adiabatic passage techniques to mediate particle transport through real space, rather than phase space is becoming an interesting possibility. We have investigated the properties of Coherent Tunneling Adiabatic Passage (CTAP) with alternating tunneling matrix elements. This geometry, not previously considered in the donor in silicon paradigm, provides an interesting route to long-range quantum transport. We introduce simplified coupling protocols, and transient eigenspectra as well as a realistic gate design for this transport protocol. Using a pairwise treatment of the tunnel coupl…

Time Dilation as Quantum Tunneling Time

We conjecture that the relative rate of time evolution depends on the amount of quantum correlations in a system. This is motivated by the experimental work [1] which showed that quantum tunneling is not instantaneous. The non-zero tunneling time may have other profound implications for the regulation of time in an entangled system. It opens the possibility that other types of quantum correlations may require non-zero rates of update. If this is true, it provides a mechanism for regulating the relative rate of time evolution.

Recovering the stationary phase condition for accurately obtaining scattering and tunneling times

The stationary phase method is often employed for computing tunneling {\em phase} times of analytically-continuous {\em gaussian} or infinite-bandwidth step pulses which collide with a potential barrier. The indiscriminate utilization of this method without considering the barrier boundary effects leads to some misconceptions in the interpretation of the phase times. After reexamining the above barrier diffusion problem where we notice the wave packet collision necessarily leads to the possibility of multiple reflected and transmitted wave packets, we study the phase times for tunneling/reflec…

超相对论区中自旋对隧穿时间的影响

Influence of spin on tunneling times in the super-relativistic regime

本研究基于狄拉克方程的替代表示构建数学模型，探究无外磁场时超相对论区自旋对隧穿时间的影响，得出隧穿时间为不同自旋粒子势垒驻留时间与自旋向上粒子自相互作用时间之和的结论。

A weak pseudo-Hermitian two band model, artificial Hawking radiation and tunneling

We examine the possibility of artificial Hawking radiation by proposing a non-PT - symmetric weakly pseudo-Hermitian two band model containing a tilting parameter. We also determine the tunneling probability using our Hamiltonian through the event horizon that acts as a classically forbidden barrier.

Delay time computation for relativistic tunneling particles

We study the tunneling zone solutions of a one-dimensional electrostatic potential for the relativistic (Dirac to Klein-Gordon) wave equation when the incoming wave packet exhibits the possibility of being almost totally transmitted through the barrier. The transmission probabilities, the phase times and the dwell times for the proposed relativistic dynamics are obtained and the conditions for the occurrence of accelerated tunneling transmission are all quantified. We show that, in some limiting cases, the analytical difficulties that arise when the stationary phase method is employed for obta…

Imaginary Time Mean-Field Method for Collective Tunneling

Background: Quantum tunneling in many-body systems is the subject of many experimental and theoretical studies in fields ranging from cold atoms to nuclear physics. However, theoretical description of quantum tunneling with strongly interacting particles, such as nucleons in atomic nuclei, remains a major challenge in quantum physics. Purpose: An initial-value approach to tunneling accounting for the degrees of freedom of each interacting particle is highly desirable. Methods: Inspired by existing methods to describe instantons with periodic solutions in imaginary time, we investigate the poss…