Scalable collective Lamb shift of a 1D superconducting qubit array in front of a mirror

Abstract

We theoretically investigate resonant dipole-dipole interaction (RDDI) between artificial atoms in a 1D geometry, implemented by N transmon qubits coupled through a transmission line. Similar to the atomic cases, RDDI comes from exchange of virtual photons of the continuous modes, and causes the so-called collective Lamb shift (CLS). To probe the shift, we effectively set one end of the transmission line as a mirror, and examine the reflection spectrum of the probe field from the other end. Our calculation shows that when a qubit is placed at the node of the standing wave formed by the incident and reflected waves, even though it is considered to be decoupled from the field, it results in large energy splitting in the spectral profile of a resonant qubit located at an antinode. This directly implies the interplay of virtual photon processes and explicitly signals the CLS. We further derive a master equation to describe the system, which can take into account mismatch of participating qubits and dephasing effects. Our calculation also demonstrates the superradiant and subradiant nature of the atomic states, and how the CLS scales when more qubits are involved.

Quantum advantage of two-level batteries in self-discharging process

“…This kind of dynamics is usually found in light mediated interaction in atomic systems [34][35][36] and superconducting qubits [32,33], for example. To illustrate our results, we consider four kind of geometries for a five-cell QB.…”

“…In particular, we assume this process in our study because it is the most common decoherence processes in a large of physical systems, e.g. in nuclear spin systems [27][28][29], cavity quantum electrodynamics [30] and superconducting qubits [31][32][33]. Then, by writing the density matrix in the QB basis |e and |g as…”

Diagrammatic Approach to Scattering of Multi-Photon States in Waveguide QED

“…In the course of the last few decades, a significant number of theoretical approaches allowing one to tackle the waveguide QED problems within this limit was proposed. In particular, the Markovian waveguide QED systems are commonly examined theoretically with help of master equation based-approaches [1,[22][23][24][25][26][27]. Indeed, within the framework of the associated input-output formalism [1,28,29], Linblad-type equation approaches allow one to study transmission and reflection characteristics, as well as the photonic correlations for arbitrary initial photon states, including coherent, thermal, and Fock ones.…”

Cooperative states and shift in resonant scattering of an atomic ensemble

“…Similar consideration applies to many-body cases, where both the real and virtual processes of photon exchange mediate the dipole-dipole interaction, resulting in cooperative decay and energy shift of the collective states. Recently, such phenomena have attracted extensive attention, and have been discussed in various contexts including atomic clouds [7,[11][12][13][14][15][16][17], one-dimensional atomic chains [18], ordered atomic arrays [19][20][21], nano-layer gases [22,23], ensembles of nuclei [24], trapped ions [25], and artificial atoms [26,27]. Another perspective views this shift as coupling between collective states, leading to Rabi-like excitation transfer among a few atoms [28].…”