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Locality of temperature
This work is concerned with thermal quantum states of Hamiltonians on spin and fermionic lattice systems with short range interactions. We provide results leading to a local definition of
Direct certification of a class of quantum simulations
TLDR
This work provides a non-interactive protocol for certifying ground states of frustration-free Hamiltonians based on simple energy measurements of local Hamiltonian terms that can be applied to classically intractable analog quantum simulations.
Boson-Sampling in the light of sample complexity
TLDR
This work shows that in this setup, with probability exponentially close to one in the number of bosons, no symmetric algorithm can distinguish the Boson-Sampling distribution from the uniform one from fewer than exponentially many samples, which means that the two distributions are operationally indisti nguishable without detailed a priori knowledge.
Positive Tensor Network Approach for Simulating Open Quantum Many-Body Systems.
TLDR
This work introduces a versatile and practical method to numerically simulate one-dimensional open quantum many-body dynamics using tensor networks, based on representing mixed quantum states in a locally purified form, which guarantees that positivity is preserved at all times.
Training Variational Quantum Algorithms Is NP-Hard.
TLDR
This work shows that the training landscape can have many far from optimal persistent local minima, which means gradient and higher order descent algorithms will generally converge to farFrom optimal solutions.
Reliable quantum certification of photonic state preparations
TLDR
An experimentally friendly and reliable certification tool for photonic quantum technologies: an efficient certification test for experimental preparations of multimode pure Gaussian states, pure non-Gaussian states generated by linear-optical circuits with Fock-basis states of constant boson number as inputs.
Dissipative quantum Church-Turing theorem.
We show that the time evolution of an open quantum system, described by a possibly time dependent Liouvillian, can be simulated by a unitary quantum circuit of a size scaling polynomially in the
Matrix-product operators and states: NP-hardness and undecidability.
TLDR
It is shown that the problem of deciding whether a given matrix-product operator actually represents a physical state that in particular has no negative eigenvalues is provably undecidable in the thermodynamic limit and that the bounded version of the problem is NP-hard (nondeterministic-polynomial-time hard) in the system size.
Quasilocality and efficient simulation of markovian quantum dynamics.
TLDR
It is concluded that the simulation on a quantum computer is additionally efficient in time and can be simulated on classical computers with a cost that is independent of the system size.
Mixing Properties of Stochastic Quantum Hamiltonians
Random quantum processes play a central role both in the study of fundamental mixing processes in quantum mechanics related to equilibration, thermalisation and fast scrambling by black holes, as
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