Josephson array of mesoscopic objects. Modulation of system properties through the chemical potential
Abstract
The phase diagram of a two-dimensional Josephson array of mesoscopic objects (superconducting granules, superfluid helium in a porous medium, traps with Bose-condensed atoms, etc.) is examined. Quantum fluctuations in both the modulus and phase of the superconducting order parameter are taken into account within a lattice boson Hubbard model. Modulating the average occupation number n0 of the sites in the system (the "number of Cooper pairs" per granule, the number of atoms in a trap, etc.) leads to changes in the state of the array, and the character of these changes depends significantly on the region of the phase diagram being examined. In the region where there are large quantum fluctuations in the phase of the superconducting order parameter, variation of the chemical potential causes oscillations with alternating superconducting (superfluid) and normal states of the array. On the other hand, in the region where the bosons interact weakly, the properties of the system depend monotonically on n0. Lowering the temperature and increasing the particle interaction force lead to a reduction in the width of the region of variation in n0 within which the system properties depend weakly on the average occupation number. The phase diagram of the array is obtained by mapping this quantum system onto a classical two-dimensional XY model with a renormalized Josephson coupling constant and is consistent with our quantum path-integral Monte Carlo calculations.
- Publication:
-
Soviet Journal of Experimental and Theoretical Physics
- Pub Date:
- August 1998
- DOI:
- 10.1134/1.558662
- arXiv:
- arXiv:cond-mat/9808123
- Bibcode:
- 1998JETP...87..322B
- Keywords:
-
- Phase Diagram;
- Hubbard Model;
- System Property;
- Cooper Pair;
- Monte Carlo Calculation;
- Condensed Matter - Mesoscale and Nanoscale Physics;
- Condensed Matter - Statistical Mechanics;
- Condensed Matter - Superconductivity
- E-Print:
- 12 pages, 8 Postscript figures