TY - JOUR

T1 - Eigenstate thermalization and representative states on subsystems

AU - Khemani, Vedika

AU - Chandran, Anushya

AU - Kim, Hyungwon

AU - Sondhi, Shivaji Lal

N1 - Publisher Copyright:
© 2014 American Physical Society.

PY - 2014/11/17

Y1 - 2014/11/17

N2 - We consider a quantum system AB made up of degrees of freedom that can be partitioned into spatially disjoint regions A and B. When the full system is in a pure state in which regions A and B are entangled, the quantum mechanics of region A described without reference to its complement is traditionally assumed to require a reduced density matrix on A. While this is certainly true as an exact matter, we argue that under many interesting circumstances expectation values of typical operators anywhere inside A can be computed from a suitable pure state on A alone, with a controlled error. We use insights from quantum statistical mechanics - specifically the eigenstate thermalization hypothesis (ETH) - to argue for the existence of such "representative states."

AB - We consider a quantum system AB made up of degrees of freedom that can be partitioned into spatially disjoint regions A and B. When the full system is in a pure state in which regions A and B are entangled, the quantum mechanics of region A described without reference to its complement is traditionally assumed to require a reduced density matrix on A. While this is certainly true as an exact matter, we argue that under many interesting circumstances expectation values of typical operators anywhere inside A can be computed from a suitable pure state on A alone, with a controlled error. We use insights from quantum statistical mechanics - specifically the eigenstate thermalization hypothesis (ETH) - to argue for the existence of such "representative states."

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U2 - 10.1103/PhysRevE.90.052133

DO - 10.1103/PhysRevE.90.052133

M3 - Article

C2 - 25493765

AN - SCOPUS:84912567468

SN - 1539-3755

VL - 90

JO - Physical Review E - Statistical, Nonlinear, and Soft Matter Physics

JF - Physical Review E - Statistical, Nonlinear, and Soft Matter Physics

IS - 5

M1 - 052133

ER -