Particle-particle correlations, characterized by Glauber’s second-order correlation function, play an important role in the understanding of various phenomena in radio and optical astronomy, quantum and atom optics, particle physics, condensed matter physics, and quantum many-body theory. However, the relevance of such correlations to quantum thermodynamics has so far remained illusive. Here, we propose and investigate a class of quantum many-body thermal machines whose operation is directly enabled by second-order atom-atom correlations in an ultracold atomic gas. More specifically, we study quantum thermal machines that operate in a sudden interaction-quench Otto cycle and utilize a one-dimensional Lieb-Liniger gas of repulsively interacting bosons as the working fluid. The atom-atom correlations in such a gas are different to those of a classical ideal gas, and are a result of the interplay between interparticle interactions, quantum statistics, and thermal fluctuations. We show that operating these thermal machines in the intended regimes, such as a heat engine, refrigerator, thermal accelerator, or heater, would be impossible without such atom-atom correlations. Our results constitute a step forward in the design of conceptually new quantum thermodynamic devices which take advantage of uniquely quantum resources such as quantum coherence, correlations, and entanglement.
YbOH molecule is one of the most sensitive systems for the electron electric dipole moment ($e$EDM) searches. Zeeman splittings of the $e$EDM sensitive levels have significant implications to control and suppress important systematic effects due to stray magnetic field in experiments for $e$EDM searches. The electric-field-dependent g factors of the lowest rotational level of the first excited bending vibrational mode of $^{174}$YbOH are calculated. l-doublet levels with small g factors difference are found and main contributions to the difference are determined.
Newly calculated multichannel quantum defect theory parameters and channel fractions are presented for the singlet and triplet S, P and D series and singlet F series of strontium. These results correct those reported in Vaillant C L, Jones M P A and Potvliege R M 2014 J. Phys. B: At. Mol. Opt. Phys. 47 155001.
The variations of exchange Slater integrals with respect to their order $k$ are not well known. While direct Slater integrals $F^k$ are positive and decreasing when the order increases, this is not stricto sensu the case for exchange integrals $G^k$. However, two inequalities were published by Racah in his seminal article "Theory of complex spectra. II". In this article, we show that the technique used by Racah can be generalized, albeit with cumbersome calculations, to derive further relations, and provide two of them, involving respectively three and four exchange integrals. Such relations can prove useful to detect regularities in complex atomic spectra and classify energy levels.
We show that the position of the exceptional points (EPs) in the parameter space of a chiral molecule coupled to the photoionization continuum by a three-color field is enantiosensitive. Using a minimal model of a three-level system driven by a three-color field to form a cyclic loop transition, we investigate the enantiosensitivity of the EPs with respect to the system parameters and exploit the asymmetric switch mechanism associated with the encirclement of an EP in parameter space in an enantio-selective way. Our work paves the way for future applications of enantiosensitive EPs in chiral systems.
Trapped atomic ion crystals are a leading platform for quantum simulations of spin systems, with programmable and long-range spin-spin interactions mediated by excitations of phonons in the crystal. We describe a complementary approach for quantum simulations of bosonic systems using phonons in trapped-ion crystals, here mediated by excitations of the trapped ion spins. The scheme features a high degree of programability over a dense graph of bosonic couplings and is suitable for hard problems such as boson sampling and simulations of long range bosonic and spin-boson Hamiltonians.
A temporal response of two interacting particles to a quench of the coupling strength in one-dimensional harmonic and anharmonic traps is explored. The coupling strength is changed from repulsive to attractive interactions and vice versa. The time evolution of the fidelity, wave packet, one-body reduced density matrix and momentum distributions is analyzed in details. It was found that impacts of the pre- and postquench states interchange during the dynamics. In the case of the anharmonic trap additional contribution of the center-of-mass excited states comes into play and the whole evolution becomes significantly altered. Yet the impact of the pre- and postquench states in some cases still could be identified. The quench dynamics of the ground and excited states are considered.
We determine the three-body bound states of an atom in a Fermi mixture. Compared to the Efimov spectrum of three atoms in vacuum, we show that the Fermi seas deform the Efimov spectrum systematically. We demonstrate that this effect is more pronounced near unitarity, for which we give an analytical estimate. We show that in the presence of Fermi seas, the three-body bound states obey a generalized discrete scaling law. For an experimental confirmation of our prediction, we propose three signatures of three-body bound states of an ultracold Fermi mixture of Yb isotopes, and provide an estimate for the onset of the bound state and the binding energy.
Using a perturbative solution for a periodically driven two-level quantum system, we show how to obtain phase factors for both a two-level quantum system and two two-level quantum systems non-interacting and interacting. The method is easily implemented by numerical routines and presents the advantage of being stable for long-time periods. We furthermore explore the possibility of implementing a quantum phase gate using the perturbative solution.
We propose a procedure to obtain exact analytical solutions to the time-dependent Schrödinger equations involving explicit time-dependent Hermitian Hamitonians from solutions to time-independent non-Hermitian Hamiltonian systems and the time-dependent Dyson relation together with the time-dependent quasi-Hermiticity relation. We illustrate the working of this method for a simple Hermitian Rabi-type model by relating it to a non-Hermitian time-independent system corresponding to the one-site lattice Yang-Lee model.
Justin T. Schultz, Azure Hansen, Nicholas P. Bigelow
We demonstrate a waveplate for a pseudo-spin-1/2 Bose-Einstein condensate using a two-photon Raman interaction. The angle of the waveplate is set by the relative phase of the optical fields, and the retardance is controlled by the pulse area. The waveplate allows us to image maps of the Stokes parameters of a Bose-Einstein condensate and thereby measure its relative ground state phase. We demonstrate the waveplate by measuring the Stokes parameters of a coreless vortex.
We demonstrate a many-atom-cavity system with a high-finesse dual-wavelength standing wave cavity in which all participating rubidium atoms are nearly identically coupled to a 780-nm cavity mode. This homogeneous coupling is enforced by a one-dimensional optical lattice formed by the field of a 1560-nm cavity mode.
The wave function of a moderately cold atom in a stationary near-resonant standing light wave delocalizes very fast due to wave packet splitting. However, we show that frequency modulation of the field may suppress packet splitting for some atoms having specific velocities in a narrow range. These atoms remain localized in a small space for a long time. We propose that in a real experiment with cold atomic gas this effect may decrease the velocity distribution of atoms (the field traps the atoms with such specific velocities while all other atoms leave the field)
Arpan Roy, Andrew Bah Shen Jing, Murray D. Barrett
We fabricate a miniature spherical mirror for tightly focusing an optical dipole trap for neutral atoms. The mirror formation process is modelled to predict the dimensions for particular fabrication parameters. We integrate the spherical mirror with a neutral atom experiment to trap and detect a single atom with high efficiency. The mirror serves the dual purpose of focusing the dipole trap as well as collection of the atomic fluorescence into an optical fibre.
Ultracold Rb atoms were used to demonstrate non-degenerate four-wave mixing through a Rydberg state. Continuous 5S-5P-nD two-photon excitation to the Rydberg state was combined with an nD-6P tuned laser in a phase matched geometry. The angular dependence, spatial profile, and dependence on detuning were investigated, showing good agreement with theory. Under optimum conditions 50 percent of the radiation was emitted into the phase-matched direction.
Hsiang-Chih Chiu, Chia-Cheng Chang, R. Castillo-Garza
et al.
Experimental methods and procedures required for precision measurements of the Casimir force are presented. In particular, the best practices for obtaining stable cantilevers, calibration of the cantilever, correction of thermal and mechanical drift, measuring the contact separation, sphere radius and the roughness are discussed.
This paper introduces and reviews light forces, atom cooling, and atom trapping. The emphasis is on the physics of the basic processes. In discussing conservative forces the semiclassical dressed states are used rather than the usual quantised-field dressed states.