Dear All,
This Friday Lior Eldar (MIT) is giving the qip seminar. Please find title and abstract
below.
Best wishes,
cyril
—
Title: On Quantum Inapproximability: or Can Entanglement Survive Outside the Fridge?
Place: 6C-442
Time: 1:30 (April 17)
Abstract: Quantum entanglement is considered to be a very delicate phenomenon that is hard
to maintain in the presence of noise, or non-zero temperatures. In recent years however,
and motivated by a quest for a quantum analog of the PCP theorem, researches have tried to
establish whether or not we can preserve quantum entanglement at constant temperature that
is independent of system size. This would imply that any quantum state with energy at
most, say 0.05 of the total available energy of the Hamiltonian, would be
highly-entangled. However to this date, no such systems were found. Moreover, it became
evident that even embedding local Hamiltonians on robust, albeit "non-physical"
topologies, namely expanders, does not guarantee entanglement robustness. In this talk,
I'll provide indication that such robustness may be possible after all, by showing a
local Hamiltonian with the following property of inapproximability: any quantum state that
violates a fraction at most 0.05 of all local terms cannot be even approximately simulated
by classical circuits whose depth is sub-logarithmic in the number of qubits. In a sense,
this implies that even providing a "witness" to the fact that the local
Hamiltonian can be "almost" satisfied, requires long-range entanglement.
--
Cyril Stark
Center for Theoretical Physics
Massachusetts Institute of Technology
77 Massachusetts Ave, 6-304
Cambridge, MA 02139, USA
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