Random quantum satisfiability

2010 ◽  
Vol 10 (1&2) ◽  
pp. 1-16
Author(s):  
C.R. Laumann ◽  
R. Moessner ◽  
A. Scarddichio ◽  
S.L. Sondhi
Keyword(s):  
Phase Transitions ◽  
Decision Problem ◽  
Quantum Phase Transitions ◽  
Quantum Computers ◽  
Sat Problem ◽  
Graph Theoretic ◽  
Theoretic Problem ◽  
Np Complete ◽  
Almost All ◽  
Complete Quantum

Alongside the effort underway to build quantum computers, it is important to better understand which classes of problems they will find easy and which others even they will find intractable. We study random ensembles of the QMA$_1$-complete quantum satisfiability (QSAT) problem introduced by Bravyi \cite{Bravyi:2006p4315}. QSAT appropriately generalizes the NP-complete classical satisfiability (SAT) problem. We show that, as the density of clauses/projectors is varied, the ensembles exhibit quantum phase transitions between phases that are satisfiable and unsatisfiable. Remarkably, almost all instances of QSAT for \emph{any} hypergraph exhibit the same dimension of the satisfying manifold. This establishes the QSAT decision problem as equivalent to a, potentially new, graph theoretic problem and that the hardest typical instances are likely to be localized in a bounded range of clause density.

Quantum phase transitions

2004 ◽  
Vol 174 (8) ◽  
pp. 853 ◽  
Author(s):  
Sergei M. Stishov
Keyword(s):  
Phase Transitions ◽  
Quantum Phase Transitions ◽  
Quantum Phase

Quantum Polaritonic

2017 ◽  
Author(s):  
Alexey V. Kavokin ◽  
Jeremy J. Baumberg ◽  
Guillaume Malpuech ◽  
Fabrice P. Laussy
Keyword(s):  
Phase Transitions ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Quantum Phase Transitions ◽  
Macroscopic Quantum ◽  
Quantum Simulations ◽  
Macroscopic Quantum Phenomena ◽  
Microcavity Polaritons ◽  
Quantum Phenomena ◽  
The One

Microcavity polaritons have demonstrated their unique propensity to host macroscopic quantum phenomena. While they appear to be highly promising for applications in a classical realm, they are still far from competing even with decade old electronics. Another playground where polaritons could emerge as strong contenders is the microscopic quantum regime with single-particle effects and nonlinearities at the one-polariton level. Several theoretical proposals exist to explore polariton blockade mechanisms, realize sophisticated quantum phase transitions, implement quantum simulations and/or quantum information processing, thereby opening a new page of the polariton physics when such ideas will be implemented in the laboratory.

scholarly journals Magnetic Field- and Pressure-Induced Quantum Phase Transitions in NH4CuCl3

2005 ◽  
Vol 159 ◽  
pp. 241-245 ◽  
Author(s):  
Masashi Fujisawa ◽  
Budhy Kurniawan ◽  
Toshio Ono ◽  
Hidekazu Tanaka
Keyword(s):  
Magnetic Field ◽  
Phase Transitions ◽  
Quantum Phase Transitions ◽  
Quantum Phase

scholarly journals Interaction between Different Kinds of Quantum Phase Transitions

2021 ◽  
Vol 3 (2) ◽  
pp. 253-261
Author(s):  
Angel Ricardo Plastino ◽  
Gustavo Luis Ferri ◽  
Angelo Plastino
Keyword(s):  
Phase Transitions ◽  
Nuclear Physics ◽  
Body Problem ◽  
Quantum Phase Transitions ◽  
Quantum Phase ◽  
Exactly Solvable Models ◽  
Solvable Models ◽  
Many Body ◽  
Pairing Interaction ◽  
Exactly Solvable

We employ two different Lipkin-like, exactly solvable models so as to display features of the competition between different fermion–fermion quantum interactions (at finite temperatures). One of our two interactions mimics the pairing interaction responsible for superconductivity. The other interaction is a monopole one that resembles the so-called quadrupole one, much used in nuclear physics as a residual interaction. The pairing versus monopole effects here observed afford for some interesting insights into the intricacies of the quantum many body problem, in particular with regards to so-called quantum phase transitions (strictly, level crossings).

scholarly journals Universal Qudit Hamiltonians

2021 ◽  
Author(s):  
Stephen Piddock ◽  
Ashley Montanaro
Keyword(s):  
State Energy ◽  
Entangled State ◽  
Quantum Computers ◽  
List Type ◽  
Universal Family ◽  
Finite Dimensional ◽  
Universal Quantum ◽  
Aklt Model ◽  
Almost All ◽  
Natural Way

AbstractA family of quantum Hamiltonians is said to be universal if any other finite-dimensional Hamiltonian can be approximately encoded within the low-energy space of a Hamiltonian from that family. If the encoding is efficient, universal families of Hamiltonians can be used as universal analogue quantum simulators and universal quantum computers, and the problem of approximately determining the ground-state energy of a Hamiltonian from a universal family is QMA-complete. One natural way to categorise Hamiltonians into families is in terms of the interactions they are built from. Here we prove universality of some important classes of interactions on qudits (d-level systems): We completely characterise the k-qudit interactions which are universal, if augmented with arbitrary Hermitian 1-local terms. We find that, for all $$k \geqslant 2$$ k ⩾ 2 and all local dimensions $$d \geqslant 2$$ d ⩾ 2 , almost all such interactions are universal aside from a simple stoquastic class. We prove universality of generalisations of the Heisenberg model that are ubiquitous in condensed-matter physics, even if free 1-local terms are not provided. We show that the SU(d) and SU(2) Heisenberg interactions are universal for all local dimensions $$d \geqslant 2$$ d ⩾ 2 (spin $$\geqslant 1/2$$ ⩾ 1 / 2 ), implying that a quantum variant of the Max-d-Cut problem is QMA-complete. We also show that for $$d=3$$ d = 3 all bilinear-biquadratic Heisenberg interactions are universal. One example is the general AKLT model. We prove universality of any interaction proportional to the projector onto a pure entangled state.

scholarly journals Entanglement View of Dynamical Quantum Phase Transitions

2021 ◽  
Vol 126 (4) ◽  
Author(s):  
Stefano De Nicola ◽  
Alexios A. Michailidis ◽  
Maksym Serbyn
Keyword(s):  
Phase Transitions ◽  
Quantum Phase Transitions ◽  
Quantum Phase

scholarly journals Quantum phase transitions in a quasi-one-dimensional Ising quantum magnet in transverse fields

2021 ◽  
Vol 103 (14) ◽  
Author(s):  
Xiaowen Zhang ◽  
Zheng He ◽  
Yiqing Hao ◽  
Yao Shen ◽  
Shoudong Shen ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Quantum Phase Transitions ◽  
Quantum Phase ◽  
One Dimensional ◽  
Quantum Magnet ◽  
Transverse Fields

scholarly journals Quantum geometric tensor and quantum phase transitions in the Lipkin-Meshkov-Glick model

2021 ◽  
Vol 103 (17) ◽  
Author(s):  
Daniel Gutiérrez-Ruiz ◽  
Diego Gonzalez ◽  
Jorge Chávez-Carlos ◽  
Jorge G. Hirsch ◽  
J. David Vergara
Keyword(s):  
Phase Transitions ◽  
Quantum Phase Transitions ◽  
Quantum Phase
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