Scott N Walck and Nathan C Hansell 2001 Eur. J. Phys. 22 343 doi:10.1088/0143-0807/22/4/309
Scott N Walck and Nathan C Hansell
Show affiliationsWe characterize and classify the quantum states of a pair of spin-½ particles in terms of the entanglement of the pair. We describe a general strategy for classifying the quantum states of entangled systems, and apply it to the simplest entangled system available - a pair of spin-½ particles. The method is based on local unitary transformations. We give a set of six parameters that describe an arbitrary pure state of a pair of spins, one of which is the entanglement of the pair. We discuss visual representations of the state of this system, and propose a visualization using a Bloch sphere for each subsystem and a disc to record the `shared' information.
Issue 4 (July 2001)
Received 15 November 2000, in final form 5 March 2001
Scott N Walck and Nathan C Hansell 2001 Eur. J. Phys. 22 343
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