QUANTUM MEASUREMENT OPERATIONS WITH NANOMAGNETS AND SQUIDS

The low-energy behaviour of 2 coupled nanomagnets or 2 coupled SQUIDs, interacting with their environment, can be described by the model of a ''Pair or Interacting Spins Coupled to an Environmental Sea'' (PISCE S). These physical systems can then be used for a measurement operatio n in which system, apparatus and environment are all treated quantum m echanically. We design a ''Bell/Coleman-Hepp'' measuring system, and s how that in principle one may design a situation in which quantum inte rference between system and apparatus can upset the usual measurement operation.