Английская Википедия:Entropy exchange

Содержание

Текст

Текст

Текст

Текст

Текст

Текст

Текст

Текст

Текст

In quantum mechanics, and especially quantum information processing, the entropy exchange of a quantum operation <math>\phi \,</math> acting on the density matrix <math>\rho_Q \,</math> of a system <math>Q \,</math> is defined as

<math>S(\rho,\phi) \equiv S[Q',R'] = S(\rho_{QR}')</math>

where <math>S(\rho_{QR}') \,</math> is the von Neumann entropy of the system <math>Q \,</math> and a fictitious purifying auxiliary system <math>R \,</math> after they are operated on by <math>\phi \,</math>. Here,

<math>\rho_{QR} = |QR\rangle\langle QR| \quad, </math>

<math>\mathrm{Tr}_R[\rho_{QR}] = \rho_Q \quad, </math>

and

<math>\rho_{QR}' = \phi[\rho_{QR}] \quad,</math>

where in the above equation <math>\phi</math> acts on <math>Q</math> leaving <math>R</math> unchanged.

References

• Шаблон:Cite book

Шаблон:Quantum-stub