Quantum Physics of Light and Matter - The Josephson Effect

  • Luca Salasnich

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This video deals with the Josephson effect, i.e. the macroscopic quantum tunneling, predicted in 1962 and observed few years later.

It is divided into 6 different segments. The first one discusses the prediction and observation of the Josephson effect, i.e. the macroscopic quantum tunneling of a large number of particles; the second segment investigates bosons in a double-well potential within the quantum field theory formalism, while the third segment derives the two-site Bose-Hubbard Hamiltonian. Te fourth segment derives the Josephson equation from the two-site Bose-Hubbard model adopting generalized coherent states; the fifth segment investigates the direct-current (DC) Josephson effect and the alternate-current (AC) Josephson effect., and the last segment studies the many-body quantum ground state of the two-site Bose-Hubbard Hamiltonian, that is a reliable model for the so-called bosonic Josephson junction.

The ideal viewer is a MSc or PhD student of Physics or Chemistry or Engineering, who will learn about the DC and AC Josephson effect, bosons in a dobule-well potential, the two-site Bose-Hubbard Hamiltonian, and the Josephson equations for superfluids and superconductors.

Introduction

This video deals with the Josephson effect, and it is ideal for a MSc or PhD student of Physics, Chemistry or Engineering.

About The Author

Luca Salasnich

Luca Salasnich is an Associate Professor of Theoretical Physics of Matter at University of Padova, Italy. He was previously a research scientist with the Italian National Research Council (CNR). Dr. Salasnich was awarded an MSc in Physics by the University of Padova in 1991, and his PhD in Theoretical Physics by the University of Florence in 1995. His fields of research are condensed matter theory and statistical physics, in particular nonlinear phenomena and macroscopic quantum effects (like superfluidity and superconductivity) in ultra-cold atomic gases and other many-body systems. At the University of Padova, Dr. Salasnich is a member of the Scientific Committee of Area 2 (Physical Sciences) and President of the Teaching Council for the BSc in Optics and Optometrics. He has written more than 130 scientific papers for international journals, with over 2500 citations.

 

About this video

Author(s)
Luca Salasnich
DOI
https://doi.org/10.1007/978-3-030-63301-1
Online ISBN
978-3-030-63301-1
Total duration
55 min
Publisher
Springer, Cham
Copyright information
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2020

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Video Transcript

[PLAYING MUSIC]

Hi. In this last video, we shall discuss a very important quantum phenomenon that is called Josephson Effect. This is a brief summary of what I will discuss. First, I will discuss with the discovery of this effect due to Brian Josephson in the ‘60s. Then it’s a simple model for we describe the model to describe the Josephson effect, and we consider Bosons in a double-well potential. adopting the quantum field theory for bosons.

I will derive the so-called two-site Bose-Hubbard model for Bosons double-well potential, and from this model, using the coherence states, I will obtain the Josephson’s equations. And from the Josephson’s equations, I will derive the main effects predicted by Josephson, namely the so-called the direct current Josephson effect and the alternate current Josephson effect.

Finally, I would consider some exact solutions for the problem of Bosons in Josephson’s junction, namely Bosons in a double-well potential, obtaining also very interesting quantum state that these states that corresponds to the one predicted by Schrodinger, the quite well-known Schrodinger Schrodinger-cat state.