Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userUniversal free-fermion multiply-excited eigenstates and their experimental signatures in 1D arrays of two-level atoms
116
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
One-dimensional subwavelength atom arrays display multiply-excited subradiant eigenstates which are reminiscent of free fermions. In this Letter, we show that such free-fermion eigenstates appear in case of a quadratic dispersion relation of the band of singly-excited states, by demonstrating that near the band-edge, Hamiltonians of the long-range resonant dipole-dipole interactions can be approximated by a nearest-neighbour-tunneling model diagonalized by Jordan-Wigner fermions. The universal mechanism for this phenomenon implies that the free-fermion ansatz extends to states with finite decay rates and we propose schemes for their observation, exploiting a physical transfer process between sub- and super-radiant free-fermion eigenstates, and by angular coincidences in the emission from a laser driven atomic array.
rate research
Read More
We suggest a regular method of achieving an extremely long lifetime of a collective singly excited state in a generic small-size ensemble of N identical atoms. The decay rate Gamma_N of such a `superdark state can be as small as Gamma_N propto Gamma(r/lambda)^{2(N-1)} (Gamma is the radiative decay rate of an individual atom, r and lambda are the system size and the wavelength of the radiation, respectively), i.e., considerably smaller than in any of the systems suggested up to now. The method is based on a special fine tuning of the atomic Hamiltonian: namely, on a proper position-dependent adjustment of atomic transition frequencies. So chosen set of the control parameters is sufficient to ensure the minimum of the spontaneous decay rate of the engineered state in a generic ensemble of atoms (`qubits).
We predict the existence of a novel interaction-induced spatial localization in a periodic array of qubits coupled to a waveguide. This localization can be described as a quantum analogue of a self-induced optical lattice between two indistinguishable photons, where one photon creates a standing wave that traps the other photon. The localization is caused by the interplay between on-site repulsion due to the photon blockade and the waveguide-mediated long-range coupling between the qubits.
Resonant light interacting with matter can support different phases of a polarizable medium, and optical bistability where two such phases coexist. Here we identify signatures of optical phase transitions and optical bistability mapped onto scattered light in planar arrays of cold atoms. Methods on how to explore such systems in superradiant, and extreme subradiant states existing outside the light cone, are proposed. The cooperativity threshold and intensity regimes for the intrinsic optical bistability, supported by resonant dipole-dipole interactions alone, are derived in several cases of interest analytically. Subradiant states require lower intensities, but stronger cooperativity for the existence of non-trivial phases than superradiant states. The transmitted light reveals the onset of phase transitions and bistability that are predicted by mean-field theory as large jumps in coherent and incoherent signals and hysteresis. In the quantum solution, traces of phase transitions are identified in enhanced quantum fluctuations of excited level populations.
We propose a method to transfer the population and control the state of two-level and three-level atoms speeding-up Adiabatic Passage techniques while keeping their robustness versus parameter variations. The method is based on supplementing the standard laser beam setup of Adiabatic Passage methods with auxiliary steering laser pulses of orthogonal polarization. This provides a shortcut to adiabaticity driving the system along the adiabatic path defined by the standard setup.
Ordered ensembles of atoms, such as atomic arrays, exhibit distinctive features from their disordered counterpart. In particular, while collective modes in disordered ensembles show a linear optical response, collective subradiant excitations of subwavelength arrays are endowed with an intrinsic non-linearity. Such non-linearity has both a coherent and a dissipative component: two excitations propagating in the array scatter off each other leading to formation of correlations and to emission into free space modes. We show how to take advantage of such non-linearity to coherently prepare a single excitation in a subradiant (dark) collective state of a one dimensional array as well as to perform an entangling operation on dark states of parallel arrays. We discuss the main source of errors represented by disorder introduced by atomic center-of-mass fluctuations, and we propose a practical way to mitigate its effects.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
