This paper reviews recent experimental and theoretical progress concerning many-body phenomena in dilute, ultracold gases. It focuses on effects beyond standard weak-coupling descriptions, such as the Mott-Hubbard transition in optical lattices, strongly interacting gases in one and two dimensions, or lowest-Landau-level physics in quasi-two-dimensional gases in fast rotation. Strong correlations in fermionic gases are discussed in optical lattices or near-Feshbach resonances in the BCS-BEC crossover.

/pdf/many-body-physics-with-ultracold-gases-552s10zfdn.pdf

Many-Body Physics with Ultracold Gases

Shell effects in nuclear masses and deformation energies

Nuclear constitution and the interpretation of fission phenomena

/pdf/study-of-nuclear-structure-by-electromagnetic-excitation-430e7edjtf.pdf

Study of Nuclear Structure by Electromagnetic Excitation with Accelerated Ions

The properties of quasi-two-dimensional semiconductor quantum dots are reviewed. Experimental techniques for measuring the electronic shell structure and the effect of magnetic fields are briefly described. The electronic structure is analyzed in terms of simple single-particle models, density-functional theory, and "exact" diagonalization methods. The spontaneous magnetization due to Hund's rule, spin-density wave states, and electron localization are addressed. As a function of the magnetic field, the electronic structure goes through several phases with qualitatively different properties. The formation of the so-called maximum-density droplet and its edge reconstruction is discussed, and the regime of strong magnetic fields in finite dot is examined. In addition, quasi-one-dimensional rings, deformed dots, and dot molecules are considered. (Less)

/pdf/electronic-structure-of-quantum-dots-c4uhdr9l0b.pdf

Electronic structure of quantum dots

Nuclear Structure, Vol. 1

The evidence for an energy gap in the intrinsic excitation spectrum of nuclei is reviewed. A possible analogy between this effect and the energy gap observed in the electronic excitation of a superconducting metal is suggested.

Possible analogy between the excitation spectra of nuclei and those of the superconducting metallic state

The effect of nuclear rotation on the pairing force in the low excited states of deformed nuclei was investigated by using the generalized Hartree-Fock method (used in superconductivity theory) to study the quantum mechanics of the effect for a reference system rotating with a rotational angular momentum I For I greater than a critical value I/sub c/, the pairing disappears and the particles perform an approximately independent motion in the average potential, resulting in an intrinsic structure orthogonal to the ground state and in rotational energies similar to those of a free Fermi gas The I/sub c/ is estimated to be approximately l2 for A approximately 180 and approximately 18 for A approximately 238, which are only slightly higher than the highest rotational states reported for these nuclei (DLC)

Effect of Nuclear Rotation on the Pairing Correlation

It is found that the concept of pseudo-spin and pseudo-oscillator quantum numbers, introduced by previous authors, can be helpful in understanding the qualitative features of quasiparticle motion in rotating potentials, for the orbits with normal parity (excluding the high j orbits). In the first part of the paper, the use of pseudo-spin in static deformed potentials is briefly reviewed.

https://iopscience.iop.org/article/10.1088/0031-8949/26/4/003/pdf

Ben R. Mottelson

Papers

Nuclear Structure, Vol. 1

Study of Nuclear Structure by Electromagnetic Excitation with Accelerated Ions

Possible analogy between the excitation spectra of nuclei and those of the superconducting metallic state

Effect of Nuclear Rotation on the Pairing Correlation

Pseudospin in Rotating Nuclear Potentials