scholarly journals Quantum simulation of parity–time symmetry breaking with a superconducting quantum processor

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Shruti Dogra ◽  
Artem A. Melnikov ◽  
Gheorghe Sorin Paraoanu
Keyword(s):  
Phase Transition ◽  
Symmetry Breaking ◽  
Critical Exponent ◽  
Quantum Effects ◽  
Quantum Simulation ◽  
Quantum Regime ◽  
Exceptional Points ◽  
Time Symmetry ◽  
Quantum Processor

Abstract The observation of genuine quantum effects in systems governed by non-Hermitian Hamiltonians has been an outstanding challenge in the field. Here we simulate the evolution under such Hamiltonians in the quantum regime on a superconducting quantum processor by using a dilation procedure involving an ancillary qubit. We observe the parity–time ($${\mathcal{PT}}$$ PT )-symmetry breaking phase transition at the exceptional points, obtain the critical exponent, and show that this transition is associated with a loss of state distinguishability. In a two-qubit setting, we show that the entanglement can be modified by local operations.

scholarly journals Manifestation of the spontaneous parity-time symmetry breaking phase transition in hot-electron photodetection based on a tri-layered metamaterial

Nanophotonics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 495-504 ◽  
Author(s):  
Qiang Bai
Keyword(s):  
Phase Transition ◽  
Theoretical Model ◽  
Symmetry Breaking ◽  
Pt Symmetry ◽  
Coupled Mode Theory ◽  
Hot Electron ◽  
Electron Device ◽  
Coupled Mode ◽  
Time Symmetry ◽  
Existence Conditions

AbstractWe theoretically and numerically demonstrate that the spontaneous parity-time (PT) symmetry breaking phase transition can be realized respectively by using two independent tuning ways in a tri-layered metamaterial that consists of periodic array of metal-semiconductor Schottky junctions. The existence conditions of PT symmetry and its phase transition are obtained by using a theoretical model based on the coupled mode theory. A hot-electron photodetection based on the same tri-layered metamaterial is proposed, which can directly show the spontaneous PT symmetry breaking phase transition in photocurrent and possesses dynamical tunability and switchability. This work extends the concept of PT symmetry into the hot-electron photodetection, enriches the functionality of the metamaterial and the hot-electron device, and has varieties of potential and important applications in optoelectronics, photodetection, photovoltaics, and photocatalytics.

scholarly journals Photochemical Methods for the Real-Time Observation of Phase Transition Processes upon Crystallization

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1726
Author(s):  
Fuyuki Ito
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Symmetry Breaking ◽  
Real Time ◽  
Fluorescence Spectra ◽  
Time Symmetry ◽  
Time Observation ◽  
Fluorescent Molecules ◽  
Real Time Observation ◽  
Crystal Phase Transformation

We have used the fluorescence detection of phase transformation dynamics of organic compounds by photochemical methods to observe a real-time symmetry breaking process. The organic fluorescent molecules vary the fluorescence spectra depending on molecular aggregated states, implying fluorescence spectroscopy can be applied to probe the evolution of the molecular-assembling process. As an example, the amorphous-to-crystal phase transformation and crystallization with symmetry breaking at droplet during the solvent evaporation of mechanofluorochromic molecules are represented in this review.

scholarly journals Rotation-time symmetry in bosonic systems and the existence of exceptional points in the absence of $${\mathscr{PT}}$$ symmetry

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ewelina Lange ◽  
Grzegorz Chimczak ◽  
Anna Kowalewska-Kudłaszyk ◽  
Karol Bartkiewicz
Keyword(s):  
Symmetry Breaking ◽  
General Type ◽  
Energy Spectra ◽  
Exceptional Points ◽  
Rotation Time ◽  
Time Symmetry ◽  
Laser Pumping ◽  
Special Cases ◽  
New Applications ◽  
Symmetric Systems

AbstractWe study symmetries of open bosonic systems in the presence of laser pumping. Non-Hermitian Hamiltonians describing these systems can be parity-time ($${{\mathscr{PT}}}$$ PT ) symmetric in special cases only. Systems exhibiting this symmetry are characterised by real-valued energy spectra and can display exceptional points, where a symmetry-breaking transition occurs. We demonstrate that there is a more general type of symmetry, i.e., rotation-time ($${\mathscr{RT}}$$ RT ) symmetry. We observe that $${\mathscr{RT}}$$ RT -symmetric non-Hermitian Hamiltonians exhibit real-valued energy spectra which can be made singular by symmetry breaking. To calculate the spectra of the studied bosonic non-diagonalisable Hamiltonians we apply diagonalisation methods based on bosonic algebra. Finally, we list a versatile set rules allowing to immediately identifying or constructing $${\mathscr{RT}}$$ RT -symmetric Hamiltonians. We believe that our results on the $${\mathscr{RT}}$$ RT -symmetric class of bosonic systems and their spectral singularities can lead to new applications inspired by those of the $${{\mathscr{PT}}}$$ PT -symmetric systems.

scholarly journals INTERPLAY OF FIXED POINTS IN SCALAR MODELS

2013 ◽  
Vol 28 (26) ◽  
pp. 1350130 ◽  
Author(s):  
S. NAGY ◽  
K. SAILER
Keyword(s):  
Phase Transition ◽  
Fixed Point ◽  
Renormalization Group ◽  
Symmetry Breaking ◽  
Critical Exponent ◽  
Correlation Length ◽  
Group Analysis ◽  
Renormalization Group Analysis ◽  
The One ◽  
Symmetric Phase

We performed the renormalization group analysis of scalar models exhibiting spontaneous symmetry breaking. It is shown that an infrared fixed point appears in the broken symmetric phase of the models, which induces a dynamical scale, that can be identified with the correlation length. This enables one to identify the type of the phase transition which shows similarity to the one appearing in the crossover scale. The critical exponent ν of the correlation length also proved to be equal in the crossover and the infrared scaling regimes.

scholarly journals Quantum Zeno effects across a parity-time symmetry breaking transition in atomic momentum space

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Tao Chen ◽  
Wei Gou ◽  
Dizhou Xie ◽  
Teng Xiao ◽  
Wei Yi ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
State Of The Art ◽  
Cold Atom ◽  
Pt Symmetry ◽  
Level System ◽  
Flexible Control ◽  
Time Symmetry ◽  
Symmetry Phase ◽  
Lattice Quantum ◽  
Atomic Momentum

AbstractWe experimentally study quantum Zeno effects in a parity-time (PT) symmetric cold atom gas periodically coupled to a reservoir. Based on the state-of-the-art control of inter-site couplings of atoms in a momentum lattice, we implement a synthetic two-level system with passive PT symmetry over two lattice sites, where an effective dissipation is introduced through repeated couplings to the rest of the lattice. Quantum Zeno (anti-Zeno) effects manifest in our experiment as the overall dissipation of the two-level system becoming suppressed (enhanced) with increasing coupling intensity or frequency. We demonstrate that quantum Zeno regimes exist in the broken PT symmetry phase, and are bounded by exceptional points separating the PT symmetric and PT broken phases, as well as by a discrete set of critical coupling frequencies. Our experiment establishes the connection between PT-symmetry-breaking transitions and quantum Zeno effects, and is extendable to higher dimensions or to interacting regimes, thanks to the flexible control with atoms in a momentum lattice.

scholarly journals Quantum effects on the BKT phase transition of two-dimensional Josephson arrays

2000 ◽  
Vol 61 (17) ◽  
pp. 11289-11292 ◽  
Author(s):  
Alessandro Cuccoli ◽  
Andrea Fubini ◽  
Valerio Tognetti ◽  
Ruggero Vaia
Keyword(s):  
Phase Transition ◽  
Quantum Effects ◽  
Two Dimensional ◽  
Josephson Arrays ◽  
Bkt Phase Transition

The flattening phase transition in systems of trapped ions

2009 ◽  
Vol 87 (10) ◽  
pp. 1425-1435 ◽  
Author(s):  
Taunia L. L. Closson ◽  
Marc R. Roussel
Keyword(s):  
Phase Transition ◽  
Critical Exponent ◽  
Order Parameter ◽  
Ion Trap ◽  
Anisotropy Parameter ◽  
Critical Value ◽  
Trapped Ions ◽  
Dimensional Structure ◽  
Flattening Process ◽  
Second Order Phase Transition

When the anisotropy of a harmonic ion trap is increased, the ions eventually collapse into a two-dimensional structure consisting of concentric shells of ions. This collapse generally behaves like a second-order phase transition. A graph of the critical value of the anisotropy parameter vs. the number of ions displays substructure closely related to the inner-shell configurations of the clusters. The critical exponent for the order parameter of this phase transition (maximum extent in the z direction) was found computationally to have the value β = 1/2. A second critical exponent related to displacements perpendicular to the z axis was found to have the value δ = 1. Using these estimates of the critical exponents, we derive an equation that relates the amplitudes of the displacements of the ions parallel to the x–y plane to the amplitudes along the z axis during the flattening process.

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