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The spectroscopic properties of a single, tightly trapped atom are studied, when the electronic levels are coupled by three laser fields in an $N$-shaped configuration of levels, whereby a $\Lambda$-type level system is weakly coupled to a…

Quantum Physics · Physics 2014-04-16 Caroline Champenois , Giovanna Morigi , Juergen Eschner

We consider inter- and intra-species pairing interactions in an asymmetrical Fermi system. Using equation of motion method, we obtain coupled mean-field equations for superfluid gap functions and population densities. We construct a phase…

Superconductivity · Physics 2014-04-24 Renyuan Liao , Khandker F. Quader

We have used optical molecular spectroscopy to probe the many-body state of paired $^6$Li atoms near a broad Feshbach resonance. The optical probe projects pairs of atoms onto a vibrational level of an excited molecule. The rate of…

Other Condensed Matter · Physics 2007-05-23 G. B. Partridge , K. E. Strecker , R. I. Kamar , M. W. Jack , R. G. Hulet

We propose to use fermionic atoms with degenerate ground and excited internal levels ($F_g\rightarrow F_e$), loaded into the motional ground state of an optical lattice with two atoms per lattice site, to realize dark states with no…

Quantum Physics · Physics 2019-12-04 A. Piñeiro Orioli , A. M. Rey

In this paper, we investigate the ground state properties of a mixture of two species of fermionic atoms in one-dimensional optical lattice, as described by the asymmetric Hubbard model. The quantum phase transition from density wave to…

Strongly Correlated Electrons · Physics 2009-11-11 Shi-Jian Gu , Rui Fan , Hai-Qing Lin

We have observed condensation of fermionic atom pairs in the BCS-BEC crossover regime. A trapped gas of fermionic 40K atoms is evaporatively cooled to quantum degeneracy and then a magnetic-field Feshbach resonance is used to control the…

Statistical Mechanics · Physics 2009-11-10 C. A. Regal , M. Greiner , D. S. Jin

We investigate a population-imbalanced two-species fermionic system where the resonantly-paired fermions combine to form bosonic molecules via Feshbach interaction. We study the dynamics of the intrinsic quantum fluctuations of the system.…

Quantum Gases · Physics 2020-12-14 Raka Dasgupta , J. K. Bhattacharjee

Superradiance, the enhanced collective emission of light from a coherent ensemble of quantum systems, has been typically studied in atomic ensembles. In this work we study the enhanced emission of energy from coherent ensembles of harmonic…

Quantum Physics · Physics 2011-07-27 Michael Delanty , Stojan Rebic , Jason Twamley

The BCS-to-BEC crossover, as well as the nature of Cooper pairs, in a superconducting and Fermi superfluid medium is studied from the exact ground state wavefunction of the reduced BCS Hamiltonian. As the strength of the interaction…

Superconductivity · Physics 2009-11-11 Gerardo Ortiz , Jorge Dukelsky

We consider a dilute two-component atomic fermion gas with unequal populations in a harmonic trap potential using the mean field theory and the local density approximation. We show that the system is phase separated into concentric shells…

Other Condensed Matter · Physics 2007-05-23 C. -H. Pao , S. -K. Yip

We determine the radio-frequency (RF) spectra for non-stationary states of a fermionic condensate produced by a rapid switch of the scattering length. The RF spectrum of the nonequilibrium state with constant BCS order parameter has two…

Superconductivity · Physics 2009-11-13 M. Dzero , E. A. Yuzbashyan , B. L. Altshuler , P. Coleman

We consider a mixture of fermionic and bosonic atoms nearby interspecies Feshbach resonances, which have been observed recently in $^6$Li-$^{23}$Na mixture by MIT group, and in $^{40}$K-$^{87}$Rb mixture by JILA group. We point out that the…

Superconductivity · Physics 2009-11-11 Jian Zhang , Hui Zhai

We study the macroscopic quantum tunneling of two weakly-linked superfluids made of interacting fermionic atoms. We derive atomic Josephson junction equations and find that zero-mode and pi-mode frequencies of coherent atomic oscillations…

Statistical Mechanics · Physics 2008-04-09 L. Salasnich , N. Manini , F. Toigo

We study the coherence properties of a trapped two-component gas of fermionic atoms below the BCS critical temperature. We propose an optical method to investigate the Cooper-pair coherence across different regions of the superfluid.…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Gh. -S. Paraoanu , M. Rodriguez , P. Torma

We present a mean field approach based on pairs of fermionic atoms to describe condensates in the BEC-BCS crossover regime. By introducing an effective potential, the mean field equation allows us to calculate the chemical potential, the…

Superconductivity · Physics 2007-05-23 Cheng Chin

We briefly discuss recent experiments on the BCS-BEC crossover with ultracold alkali-metal atoms both in three-dimensional configurations and two-dimensional ones. Then we analyze the quantum-field-theory formalism used to describe an…

Quantum Gases · Physics 2016-02-26 L. Salasnich

We investigate here the Cooper pairing of fermionic atoms with mismatched fermi surfaces using a variational construct for the ground state. We determine the state for different values of the mismatch of chemical potential for weak as well…

Superconductivity · Physics 2014-11-17 Amruta Mishra , Hiranmaya Mishra

Ultra-cold Fermi gases display diverse quantum mechanical properties, including the transition from a fermionic superfluid BCS state to a bosonic superfluid BEC state, which can be probed experimentally with high precision. However, the…

We predict the possibility of sharp, high-contrast resonances in the optical response of a broad class of systems, wherein interference effects are generated by coherent perturbation or interaction of dark states. The properties of these…

Quantum Physics · Physics 2009-10-31 M. D. Lukin , S. F. Yelin , M. Fleischhauer , M. O. Scully

We present the calculation of the coherent spectral functions and density of states (DOS) for excitonic systems in the frame of the three dimensional extended Falicov-Kimball model. By using gauge-invariant U(1) transformation to the usual…

Strongly Correlated Electrons · Physics 2015-08-04 V. Apinyan , T. K. Kopeć