The light-matter butterfly

The quantum computation is a new scheme for computation based on the quantum physics, which is much more efficient than the digital computation algorithms. The quantum information are stored at quantum bits (qubits). In one implementation of a quantum computer, light is used as a mediator to transport information as well as to manipulate the qubits. The simplest setup to let the light and qubit interact consists of an atom (qubit) surrounded by a pair of mirrors (cavity). In this way, light meets the qubit many times as it bounces off the mirrors and becomes strongly coupled to it. This is then used to read off the qubit state or to perform basic logic operations. My research aims at understanding the physics of composite systems made out of hundreds of these blocks and eventually scaling up to build a quantum computer. Here, we use quantum mechanics to study a dimer system including only two coupled blocks where the light can travel from one to another. The figure shows the energy eigen-spectrum of this system; i.e. how the light is distributed in each quantum state. The complicated structure exhibits the rich physics for even such a small system.Ope