856,187 research outputs found
Dimensional hybridity in measurement-induced criticality
Entanglement transitions in quantum dynamics present a novel class of phase
transitions in non-equilibrium systems. When a many-body quantum system
undergoes hybrid quantum dynamics, consisting of unitary evolution interspersed
with monitored random measurements, the steady-state can exhibit a phase
transition between volume- and area-law entanglement. The role of dimension in
the nature of these transitions is an open problem. There is a dimensional
correspondence between measurement-induced transitions in non-unitary quantum
circuits in spatial dimensions and classical statistical mechanical models
in dimensions, where the time dimension in the quantum problem is mapped
to a spatial dimension in the classical model. In this work we show that the
role of dimension is considerably richer by unveiling a form of `dimensional
hybridity': critical properties of the steady-state entanglement are governed
by a combination of exponents consistent with -dimensional percolation and
-dimensional percolation. We uncover this dimensional hybridity in 1+1D
and 2+1D circuits using a graph-state based simulation algorithm where the
entanglement structure is encoded in an underlying graph, providing access to
the geometric structure of entanglement. We locate the critical point using the
tripartite information, revealing area-law entanglement scaling at criticality,
and showing that the entanglement transition coincides with the purification
transition. The emergence of this `dimensional hybridity' in these non-unitary
quantum circuits sheds new light on the universality of measurement-induced
transitions, and opens the way for analyzing the quantum error correcting
properties of random unitary circuits in higher dimensions.Comment: 17 pages, 15 figures. Updated estimates of surface exponents
and $\eta_\bot
MatSWMM - An open-source toolbox for designing real-time control of urban drainage systems
This manuscript describes the MatSWMM toolbox, an open-source Matlab, Python, and LabVIEW-based software package for the analysis and design of real-time control (RTC) strategies in urban drainage systems (UDS). MatSWMM includes control-oriented models of UDS, and the storm water management model (SWMM) of the US Environmental Protection Agency (EPA), as well as systematic-system edition functionalities. Furthermore, MatSWMM is also provided with a population-dynamics-based controller for UDS with three of the fundamental dynamics, i.e., the Smith, projection, and replicator dynamics. The simulation algorithm, and a detailed description of the features of MatSWMM are presented in this manuscript in order to illustrate the capabilities that the tool has for educational and research purposes.Peer ReviewedPostprint (author's final draft
Open problems in artificial life
This article lists fourteen open problems in artificial life, each of which is a grand challenge requiring a major advance on a fundamental issue for its solution. Each problem is briefly explained, and, where deemed helpful, some promising paths to its solution are indicated
Entanglement in a fermion chain under continuous monitoring
We study the entanglement entropy of the quantum trajectories of a free
fermion chain under continuous monitoring of local occupation numbers. We
propose a simple theory for entanglement entropy evolution from disentangled
and highly excited initial states. It is based on generalized hydrodynamics and
the quasi-particle pair approach to entanglement in integrable systems. We test
several quantitative predictions of the theory against extensive numerics and
find good agreement. In particular, the volume law entanglement is destroyed by
the presence of arbitrarily weak measurement.Comment: 18 pages, 8 figures, 2 new figure
Towards Laser Control of Open Quantum Systems: Memory Effects
Laser control of Open Quantum Systems (OQS) is a challenging issue as
compared to its counterpart in isolated small size molecules, basically due to
very large numbers of degrees of freedom to be accounted for. Such a control
aims at appropriately optimizing decoherence processes of a central two-level
system (a given vibrational mode, for instance) towards its environmental bath
(including, for instance, all other normal modes). A variety of applications
could potentially be envisioned, either to preserve the central system from
decaying (long duration molecular alignment or orientation, qubit decoherence
protection) or, to speed up the information flow towards the bath (efficient
charge or proton transfers in long chain organic compounds). Achieving such
controls require some quantitative measures of decoherence in relation with
memory effects in the bath response, actually given by the degree of
non-Markovianity. Characteristic decoherence rates of a Spin-Boson model are
calculated using a Nakajima-Zwanzig type master equation with converged HEOM
expansion for the memory kernel. It is shown that, by adequately tuning the
two-level transition frequency through a controlled Stark shift produced by an
external laser field, non-Markovianity can be enhanced in a continuous way
leading to a first attempt towards the control of OQS
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