Ninety-five-years lasting mystery of quantum-tunneling time had been solved essentially in 2022 based on a novel understanding of the tunneling mechanism. It would be technologically beneficial and even lead to amazing changes in fundamental physics.
In this essay I survey recent developments in the theory of tunnelling times in quantum mechanics. The study of this concept is polarised depending on one’s interpretation of quantum mechanics, which require different approaches and yield starkly different results. I survey this topic through the lenses of the orthodox (Copenhagen) and de Broglie-Bohm (pilot wave) interpretations, presenting the requisite theory and definitions and expounding the literature of the original authors through proofs and figures. I do this in sections 2 and 3 respectively. Before embarking on tunnelling times as a topic, I survey the conceptual aspects of how time is treated in classical and quantum mechanics. This topic has many subtle aspects which have hindered progress in understanding tunnelling times in the past. In this essay I hope to demonstrate the success that has been achieved in recent years, but also that further theoretical and experimental work is required, if we are to arrive at a universally accepted definition of tunnelling times in quantum mechanics - if indeed such a definition exists.
How come such a successful theory like Quantum Mechanics has so many
mysteries? The history of this theory is replete with dubious interpretations
and controversies. The knowledge of its predictions, however, caused the
amazing technological revolution of the last hundred years. In its very
beginning Einstein pointed out that there was something missing due to
contradictions with the relativity theory. So, even though Quantum Mechanics
explains all the physical phenomena, due to its mysteries, there were many
attempts to find a way to ``complete it, e.g. hidden-variable theories. In
this paper, we present these mysteries, with special attention to the concepts
of physical reality imposed by quantum mechanics, the role of the observer,
prediction limits, definition of collapse, and how to deal with correlated
states (the basic strategy for quantum computers and quantum teleportation).
The discussion is carried out by accepting that there is nothing important
missing. We are just restricted by the limitations imposed by quantum
mechanics. The mysteries are cleared out by a proper interpretation of these
limitations. This is done by introducing two interpretation rules within the
Copenhagen interpretation.
Quantum particles interacting with potential barriers are ubiquitous in physics, and the question of how much time they spend inside classically forbidden regions has attracted interest for many decades. Recent developments of new experimental techniques revived the issue and ignited a debate with often contradictory results. This motivates the present study of an exactly solvable model for quantum tunneling induced by a strong field. We show that the tunneling dynamics can depart significantly from the scenario in which the barrier-traversal time is zero or very small. However, our findings do not support the idea of a well-defined tunneling time either. Our numerically exact results should help in finding a consensus about this fundamental problem.
Why does such a successful theory like Quantum Mechanics have so many mysteries? The history of this theory is replete with dubious interpretations and controversies, and yet a knowledge of its predictions, however, contributed to the amazing technological revolution of the last hundred years. In its very beginning Einstein pointed out that there was something missing, due to contradictions with the relativity theory. So, even though Quantum Mechanics explains all the nanoscale physical phenomena, there were many attempts to find a way to “complete” it, e.g. hidden-variable theories. In this paper, we discuss some of those enigmas, with special attention to the concepts of physical reality imposed by quantum mechanics, the role of the observer, prediction limits, a definition of collapse, and how to deal with correlated states (the basic strategy for quantum computers and quantum teleportation). That discussion is carried out within the framework of accepting that there is in fact nothing important missing, rather we are just restricted by the limitations imposed by quantum mechanics. The mysteries are thus explained by a proper interpretation of those limitations, which is achieved by introducing two interpretation rules within the Copenhagen paradigm.
Abstract How long does a quantum particle take to traverse a classically forbidden energy barrier? In other words, what is the correct expression for quantum tunnelling time? This seemingly simple question has inspired widespread debate in the physics literature. I argue that we should not expect the orthodox interpretation of quantum mechanics to provide a unique correct expression for quantum tunnelling time, because to do so it would have to provide a unique correct answer to a question whose assumptions are in tension with its core interpretational commitments. I explain how this conclusion connects to time’s special status in quantum mechanics, the meaningfulness of classically inspired concepts in different interpretations of quantum mechanics, the prospect of constructing experimental tests to distinguish between different interpretations, and the status of weak measurement in resolving questions about the histories of subensembles.
The initiation of the field ‘quantum biology’ didn’t take too long following the establishment of quantum mechanics during the late 19th century to the early 20th century. In the late 1920s, Bohr delivered a lecture on the possibility of using quantum mechanics in solving the mysteries of life. However, since the 1940s, the field has started getting considerable attention following the publication of Schrödinger’s book on defining life using physics principles. During the last hundred years of research in quantum biology, we have accomplished considerable progress in understanding crucial issues around key biology problems. In this chapter, I shall focus on summarizing most of the areas of biology where the quantum mechanical interventions have helped us understand underlying mechanisms. We could develop some applied technologies involving quantum principles that might be utilized to understand biological diseases and intervene in the associated disorders with appropriate means. A pinpointed historical progression in this novel field of research will mostly be presented. Thus, the information here will help readers and interested researchers understand the field properly and plan for new projects aiming at creating future breakthroughs.