Concentration of Measure for Quantum States with a Fixed Expectation Value
Given some observable H on a finite-dimensional quantum system, we investigate the typical properties of random state vectors that have a fixed expectation value with respect to H . Under some conditions on the spectrum, we prove that this manifold of quantum states shows a concentration of measure...
Uloženo v:
| Vydáno v: | Communications in mathematical physics Ročník 303; číslo 3; s. 785 - 824 |
|---|---|
| Hlavní autoři: | , , |
| Médium: | Journal Article |
| Jazyk: | angličtina |
| Vydáno: |
Berlin/Heidelberg
Springer-Verlag
01.05.2011
Springer |
| Témata: | |
| ISSN: | 0010-3616, 1432-0916 |
| On-line přístup: | Získat plný text |
| Tagy: |
Přidat tag
Žádné tagy, Buďte první, kdo vytvoří štítek k tomuto záznamu!
|
| Shrnutí: | Given some observable
H
on a finite-dimensional quantum system, we investigate the typical properties of random state vectors
that have a fixed expectation value
with respect to
H
. Under some conditions on the spectrum, we prove that this manifold of quantum states shows a concentration of measure phenomenon: any continuous function on this set is almost everywhere close to its mean. We also give a method to estimate the corresponding expectation values analytically, and we prove a formula for the typical reduced density matrix in the case that
H
is a sum of local observables. We discuss the implications of our results as new proof tools in quantum information theory and to study phenomena in quantum statistical mechanics. As a by-product, we derive a method to sample the resulting distribution numerically, which generalizes the well-known Gaussian method to draw random states from the sphere. |
|---|---|
| ISSN: | 0010-3616 1432-0916 |
| DOI: | 10.1007/s00220-011-1205-1 |