Quantum Coherence and Decoherence in Model Spin Systems
Abstract
Platforms for quantum computation have to walk the fine line between isolation from the environment to preserve coherent quantum manipulation and addressability for programming and readout. The fundamental quantum mechanics of coherence, decoherence, and control is often difficult to discern in actual quantum computing architectures, and can benefit from studies of model quantum spin systems. We perform a carefully chosen set of experiments on a physical realization of the Ising model in transverse field, whose behavior is dominated by quantum-mechanically self-assembled spin clusters; a putative quantum spin liquid, dominated by the disruptive effects of quantum fluctuations; and a rare earth magnet on the cusp of a quantum phase transition, where the spatial extent of coherent order diverges at the transition and becomes hypersensitive to disorder. These experiments utilize a broad spectrum of techniques to gain a fuller understanding of the underlying physics. Temperatures below 1 Kelvin and pressures above 200,000 atmospheres tune the systems into the desired states. Probes such as ac susceptibility and heat capacity measure the energy and magnetic configuration, and GHz microwave spectroscopy probes low-lying excited states, allowing us to quantitatively understand the effects of disorder. In all of these experiments, we take advantage of the fact that quantum fluctuations and extended states can be sensitive probes for decoherence mechanisms. Highly entangled spin systems with extended correlations such as quantum spin liquids and quantum critical points separating ordered and disordered magnetic states realize the underlying physics of a successful quantum computer. In and of themselves they may not be programmable, but they permit quantitative statements about decoherence over large spatial extents. They also admit to non-thermal tuning parameters to manipulate coherence, dissipation, and long-range order.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502510017
Entities
People
- Daniel Silevitch
Organizations
- Air Force Office of Scientific Research
- California Institute of Technology
- United States Air Force