Damping of Vacuum Rabi Oscillations in a Two-Qubit Structure in a High-Q Cavity
- PDF / 1,105,849 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 104 Downloads / 178 Views
RCONDUCTIVITY
Damping of Vacuum Rabi Oscillations in a Two-Qubit Structure in a High-Q Cavity O. A. Chuikina, Ya. S. Greenberga,*, and A. A. Shtygasheva a Novosibirsk
State Technical University, Novosibirsk, 630073 Russia *e-mail: [email protected]
Received March 26, 2020; revised March 26, 2020; accepted April 2, 2020
Abstract—The article studies the attenuation of vacuum Rabi oscillations for a system of two superconducting solid-state qubits placed in a high-Q microwave cavity. Two different cases are considered in which: 1) the first qubit is excited at the initial time and 2) the initial state comprises an entangled symmetric and antisymmetric pair of states. The dependence of the attenuation on various parameters, primarily on the coupling constant between qubits and the field and on the distance between qubits, is studied in detail. It is shown that, for some parameters, the relaxation time of the excited state of a qubit in such a system is significantly longer than that of a single qubit in the cavity. Keywords: superconducting qubits, microwave cavity, vacuum Rabi oscillations, coherence time DOI: 10.1134/S106378342009005X
1. INTRODUCTION Rabi oscillations are a well-known effect, according to which, in a two-level system interacting with radiation, population oscillates at a frequency proportional to the coupling coefficient between the system and the electromagnetic field. This phenomenon was first studied by Rabi in 1937 [1] for atomic spins in a magnetic field. The original approach considered the electromagnetic field classically, in the form of harmonic waves acting on an atom. Later, in 1963, Jaynes and Cummings derived a quantum Rabi model, considering the field a set of photons [2]. This model is of fundamental importance, since it considers the interaction of radiation with matter at the most basic level. It explained some effects that do not arise in the semiclassical model, in particular, the so-called vacuum Rabi oscillations, when, even in the absence of an external electromagnetic field, the two-level system, which was initially in an excited state, undergoes population oscillations due to the interaction of the system with the so-called vacuum fluctuations in the energy of the electromagnetic field [3]. Since recently, due to the significant development of experimental quantum optics [4] and quantum informatics [5], Rabi oscillations have become the subject of intensive theoretical [6–9] and experimental [10–13] studies. In real systems, Rabi oscillations decay with time due to energy losses and interactions with the ambient medium. This effect is extremely important for applications, since it essentially determines the lifetime of a quantum system. It is especially important for quantum informatics, where the lifetime of a qubit (quan-
tum two-level system) in an excited state determines the number of operations that can be performed using it [5]. The damping of Rabi oscillations is due to relaxation: spontaneous emission and nonradiative decay, as well as decoherence: the loss
Data Loading...
