Dynamic nonlinear (cubic) susceptibility in quantum d-dimensional Ising spin Glass with short-range interactions is investigated on the basis of quantum droplet model and quantum-mechanical nonlinear response theory. Nonlinear response depends on the tunneling rate for a droplet which regulates the strength of quantum fluctuations. It shows it strong dependence on the distribution of droplet free energies and on the droplet length scale average. Comparison with recent experiments on quantum spin Glasses like disordered dipolar quantum Ising magnet is discussed. (C) 2002 Elsevier Science Ltd. All rights reserved. References: 35
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