Resonance Fluorescence of a Single Artificial Atom

Abstract

An atom in open space can be detected by means of resonant absorption and reemission of electromagnetic waves, known as resonance fluorescence, which is a fundamental phenomenon of quantum optics. We report on the observation of scattering of propagating waves by a single artificial atom. The behavior of the artificial atom, a superconducting macroscopic two-level system, is in a quantitative agreement with the predictions of quantum optics for a pointlike scatterer interacting with the electromagnetic field in one-dimensional open space. The strong atom-field interaction as revealed in a high degree of extinction of propagating waves will allow applications of controllable artificial atoms in quantum optics and photonics.A single atom interacting with electromagnetic modes of free space is a fundamental example of an open quantum system (Fig. 1A) [1]. The interaction between the atom (or molecule, quantum dot, et cetera) and a resonant electromagnetic field is particularly important for quantum electronics and quantum information processing. In three-dimensional (3D) space, however, although perfect coupling (with 100% extinction of transmitted power) is theoretically feasible [2], experimentally achieved extinction has not exceeded 12% [3][4][5][6][7] because of spatial mode mismatch between incident and scattered waves. This problem can be avoided by an efficient coupling of the atom to the continuum of electromagnetic modes confined in a 1D transmission line (Fig. 1B) as proposed in [8,9]. Here we demonstrate extinction of 94% on an artificial atom coupled to the open 1D transmission line. The situation with the atom interacting with freely propagating waves is qualitatively different from that of the atom interacting with a single cavity mode; the latter has been used to demonstrate a series of cavity quantum electrodynamics (QED) phenomena [10][11][12][13][14][15][16][17][18]. Moreover in open space, the atom directly reveals such phenomena known from quantum optics as anomalous dispersion and strongly nonlinear behavior in elastic (Rayleigh) scattering near the atomic resonance[1]. Furthermore, spectrum of inelastically scattered radiation is observed and exhibits the resonance fluorescence triplet (the Mollow triplet) [19][20][21][22][23] under a strong drive.Our artificial atom is a macroscopic superconducting loop, interrupted by Josephson junctions (Fig. 1B) [identical to a flux qubit [24]] and threaded by a bias flux Φ b close to a half flux quantum Φ 0 /2, and shares a segment with the transmission line [25], which results in a loop-line mutual inductance M mainly due to kinetic * On leave from Physical-Technical Institute, Tashkent 100012, Uzbekistan † On leave from Lebedev Physical Institute, Moscow 119991, Russia inductance of the shared segment [26]. The two lowest eigenstates of the atom are naturally expressed via superpositions of two states with persistent current, I p , flowing clockwise or counterclockwise. In energy eigenbasis the lowest two levels |g and |e are described by the truncated...

Quantum electrodynamics near a photonic bandgap

“…In Fig. 2(a), we observe that the bound state peak below the band edge persists while the input signal at the bare qubit frequency is completely reflected due to destructive interference [19]. Now we can extract ω q , ω b and fit the data to Equation (3).…”

“…In contrast to a system with discrete cavity modes, which is well described by the single mode or multimode Jaynes-Cummings Hamiltonian [16,17,18], a continuous density of states enables the formation of a localized state in the band gap. While other spin-boson problems with continuous DOS have also been studied experimentally [19,20] or theoretically [21,22] with superconducting circuits, this work explores physics near the band edge, where localized states emerge and reservoir engineering becomes possible.Light-matter interactions are being actively pursued using cold atoms coupled to optical photonic crystals [23,24], where the study of photonic band edge effects requires a combination of challenging nanostructure fabrication and optical laser trapping. Though impressive progress has been made, atoms are only weakly coupled to photonic crystal waveguides [24], potentially limiting the physics to the the perturbative regime.…”

“…In contrast to a system with discrete cavity modes, which is well described by the single mode or multimode Jaynes-Cummings Hamiltonian [16,17,18], a continuous density of states enables the formation of a localized state in the band gap. While other spin-boson problems with continuous DOS have also been studied experimentally [19,20] or theoretically [21,22] with superconducting circuits, this work explores physics near the band edge, where localized states emerge and reservoir engineering becomes possible.…”

Dual-channel spontaneous emission of quantum dots in magnetic metamaterials

“…Overcoming this major obstacle would lead to novel functional materials based on the control of both electric and magnetic material responses at optical frequencies, namely, to negative refractive index [10][11][12] , chirality [13][14][15][16][17][18] and subwavelength imaging 19 as well as to compact nanolasers and spasers 20,21 . Finally, active metamaterials might also enter new, unexplored areas such as quantum metamaterials [22][23][24] . In recent years, strong efforts have been made to find practical ways of reducing losses in optical metamaterials 21,[25][26][27][28][29] , leading to the first demonstration of a loss-compensated negative-index metamaterial 26 .…”

Nonequilibrium quantum transport through a dissipative resonant level

“…Dissipation-driven QPTs have been addressed theoretically and experimentally in various systems, such as: quantum dot systems 9,47 , Josephson junction arrays [48][49][50] , superconducting thin film [51][52][53] , superconducting qubit 54 , qubits or resonant level systems coupled to photonic cavities 55,56 , and biological systems 45,57 . Very recently, new Majorana physics in dissipative nano-structures has attracted much attention 58 .…”