Lecture

Quantum Couplers: Hamiltonians and Coupling Mechanisms

Graph Chat

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

In course

MICRO-444: La science quantique : une vision singulière

Les étudiants comprennent les caractéristiques de la science quantique. Ils en maitrisent le formalisme et l'appliquent dans les systèmes de base: puits, fils et boites quantiques, qubits. ...

Description

This lecture focuses on the concept of quantum couplers, particularly Hamiltonians and their coupling mechanisms. The instructor begins by reviewing Hamiltonians, emphasizing their diagonal structure and the significance of coupling terms. The discussion includes the Hamiltonian for a single qubit and the associated propagator, highlighting the rotation dynamics on the Bloch sphere. The instructor explains the Larmor frequency and its relation to energy differences between states. The lecture progresses to symmetric double wells and coupled modes, illustrating how these systems can be analyzed using Hamiltonians. The instructor introduces the Josephson junction as a nonlinear inductance, explaining its role in quantum circuits and the tunneling effect between Cooper pairs. The lecture concludes with a discussion on the formation of energy bands in coupled wells and the implications for quantum computing, particularly in the context of qubit coupling and measurement techniques. Overall, the lecture provides a comprehensive overview of the theoretical foundations and practical applications of quantum couplers in quantum science.

Instructor

Pierre-André Besse

Teaching & PhD Past EPFL PhD Students Klaus Ehrmann Courses La science quantique : une vision singulière MICRO-444 Students understand the characteristics of quantum science. They master the formalism and use it in basic quantum systems: quantum wells, wires, dots or qubits. Physics of semiconductors devices MICRO-312 The students are able to explain the physics of semiconductor devices like diodes, transistors, and MOS devices. They use such devices in fundamental electroni

Official source

Ontological neighbourhood

Theoretical computer science

Theory of computation: Quantum computing

Related concepts (32)

Quantum computing

A quantum computer is a computer that exploits quantum mechanical phenomena. At small scales, physical matter exhibits properties of both particles and waves, and quantum computing leverages this behavior, specifically quantum superposition and entanglement, using specialized hardware that supports the preparation and manipulation of quantum states. Classical physics cannot explain the operation of these quantum devices, and a scalable quantum computer could perform some calculations exponentially faster than any modern "classical" computer.

Quantum mechanics

Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science. Classical physics, the collection of theories that existed before the advent of quantum mechanics, describes many aspects of nature at an ordinary (macroscopic) scale, but is not sufficient for describing them at small (atomic and subatomic) scales.

Josephson effect

In physics, the Josephson effect is a phenomenon that occurs when two superconductors are placed in proximity, with some barrier or restriction between them. It is an example of a macroscopic quantum phenomenon, where the effects of quantum mechanics are observable at ordinary, rather than atomic, scale. The Josephson effect has many practical applications because it exhibits a precise relationship between different physical measures, such as voltage and frequency, facilitating highly accurate measurements.

Superconducting quantum computing

Superconducting quantum computing is a branch of solid state quantum computing that implements superconducting electronic circuits using superconducting qubits as artificial atoms, or quantum dots. For superconducting qubits, the two logic states are the ground state and the excited state, denoted respectively. Research in superconducting quantum computing is conducted by companies such as Google, IBM, IMEC, BBN Technologies, Rigetti, and Intel. Many recently developed QPUs (quantum processing units, or quantum chips) utilize superconducting architecture.

Quantum information

Quantum information is the information of the state of a quantum system. It is the basic entity of study in quantum information theory, and can be manipulated using quantum information processing techniques. Quantum information refers to both the technical definition in terms of Von Neumann entropy and the general computational term. It is an interdisciplinary field that involves quantum mechanics, computer science, information theory, philosophy and cryptography among other fields.

Related lectures (64)

Quantum Computing Basics

Covers the basics of quantum computing, focusing on superconducting qubits, scaling challenges, and potential applications.

Polarisation of Photons

Explores photon polarisation, including linear, circular, and elliptical polarisation concepts.

Coupling Capacitive: Two Qubits Interaction

Covers the capacitive coupling of two qubits and its implications in quantum mechanics.

Bloch sphere representation and Larmor precession

Covers the Bloch sphere representation and Larmor precession in spin 1/2 systems.

Superconducting Qubits: Non-Demolition Measurements and Control Techniques