Narrow Results

The phenomenon of tunneling is well-known in quantum theory, however, many novel characteristics appear when the corresponding classical dynamics of the underlying system is chaotic. In this paper, the chaos-assisted tunneling is found in a triple-well potential under an external periodic driving field. We make use of the Husimi distribution to illustrate this characteristic in the quantum phase-space.

A two-dimensional problem of tunneling of a particle is studied to propose an experiment to measure tunneling time. We consider a 2D rectangular barrier in which the particle undergoes both tunneling and free lateral motion at the same time. The two processes are coupled by the same tunneling time, which leads to a simple relation between the tunneling time and the corresponding lateral shift such that L = vτ. Since the lateral speed v is constant the tunneling time can be obtained by measuring the lateral shift. The shifted length can be controlled by an initial lateral speed and become over a hundred nanometers when the particle is provided with sufficient initial lateral speed. The present model may also be used for examining the relationships between characteristic tunneling times suggested in previous articles. We also demonstrate physical differences between the 2D problem of a particle tunneling and the frustrated total internal reflection of electromagnetic waves.

The time-dilations that arise during quantum tunneling appear applicable to the time-translation thought experiment by Aharonov et al. It may be feasible to actually perform a test for communicating in reverse-time as described by Cramer.

A feasible quantum means for laboratory testing the time-translation theory by Aharonov et al. has previously been proposed. If such tests prove successful, a modified test based on this model is suggested to further investigate anticipated behavioral characteristics of the Many Worlds Interpretation and quantum decoherence.

We present a simple non-Hermitian model to describe the phenomenon of asymmetric tunneling between two energy-degenerate sites coupled by a non-reciprocal interaction without dissipation. The system was described using a biorthogonal family of energy eigenvectors, the dynamics of the system was determined by the Schrödinger equation, and unitarity was effectively restored by proper normalization of the state vectors. The results show that the tunneling rates are indeed asymmetrical in this model, leading to an equilibrium that displays unequal occupation of the degenerate systems even in the absence of external interactions.

In this paper, the interaction and transmission time of quantum density solitons waves [B. M. Mirza, Mod. Phys. Lett. B 28 (2014) 1450200]¹ passing through finite barrier potentials is investigated. Using the conservation of energy and of quantum density, it is first demonstrated that the soliton waves possess the important particle-like properties, including localization by a finite de Broglie wavelength and constant uniform motion in free space. The passage of quantum density solitons through barriers of finite energies is then shown to lead to the phenomena of resonant tunneling and, in Josephson-like configurations, to the quantization of magnetic flux. A precise general measure for barrier tunneling time is derived which is found to give a new interpretation of the quantum indeterminacy principles. The quantum density soliton theory is applied to coherent microstructures observed in NbSe₃-like systems, where it is shown to lead to the sawtooth current phenomena and nano-scale transversal times.

Quantum tunneling events occurring through biochemical bonds are capable of generating quantum correlations between bonded systems, which in turn makes the conventional second law of thermodynamics approach insufficient to investigate these systems. This means that the utilization of these correlations in their biological functions could give an evolutionary advantage to biomolecules to an extent beyond the predictions of molecular biology that are generally based on the second law in its standard form. To explore this possibility, we first compare the tunneling assisted quantum entanglement shared in the ground states of covalent and hydrogen bonds. Only the latter appears to be useful from a quantum information point of view. Also, significant amounts of quantum entanglement can be found in the thermal state of hydrogen bond. Then, we focus on an illustrative example of ligand binding in which a receptor protein or an enzyme is restricted to recognize its ligands using the same set of proton-acceptors and donors residing on its binding site. In particular, we show that such a biomolecule can discriminate between $3^n-1$ agonist ligands if it uses the entanglement shared in $n$ intermolecular hydrogen bonds as a resource in molecular recognition. Finally, we consider the molecular recognition events encountered in both the contemporary genetic machinery and its hypothetical primordial ancestor in pre-DNA world, and discuss whether there may have been a place for the utilization of quantum entanglement in the evolutionary history of this system.