Signature of nonequilibrium quantum **phase** **transition** in the long time
average of Loschmidt echo

**phase**

**transitions**are characterized by the emergence of a series of zero points at critical times during time evolution, we demonstrate that nonequilibrium quantum phase

**transition**s can be identified by nonanalyticities in the long time average of Loschmidt echo. Expand abstract.

**phase**

**transitions**by studying sudden quench processes across quantum

**phase**

**transitions**in various quantum systems. While the dynamical quantum

**phase**

**transitions**are characterized by the emergence of a series of zero points at critical times during time evolution, we demonstrate that nonequilibrium quantum

**phase**

**transitions**can be identified by nonanalyticities in the long time average of Loschmidt echo. The nonanalytic behaviours are illustrated by a sharp change in the long time average of Loschmidt echo or the corresponding rate function or the emergence of divergence in the second derivative of rate function when the driving quench parameter crosses the

**phase**

**transition**points. The connection between the second derivative of rate function and fidelity susceptibility is also discussed.

10/10 relevant

arXiv

Fragmentation **phase** **transition** in atomic clusters I --- Microcanonical
thermodynamics

**phase**

**transitions**of first and second order in systems which are thermodynamically stable in the sense of van Hove. We show how both kinds of

**phase**

**transitions**can unambiguously be identified in relatively small isolated systems of $\sim 100$ atoms by the shape of the microcanonical caloric equation of state $$ I.e. within microcanonical thermodynamics one does not need to go to the thermodynamic limit in order to identify

**phase**

**transitions**. In contrast to ordinary (canonical) thermodynamics of the bulk microcanonical thermodynamics (MT) gives an insight into the coexistence region. The essential three parameters which identify the

**transition**to be of first order, the

**transition**temperature $T_{tr}$, the latent heat $q_{lat}$, and the interphase surface entropy $\Delta s_{surf}$ can very well be determined in relatively small systems like clusters by MT. The

**phase**

**transition**towards fragmentation is introduced. The general features of MT as applied to the fragmentation of atomic clusters are discussed. The similarities and differences to the boiling of macrosystems are pointed out.

10/10 relevant

arXiv

Quasiparticles as Detector of Topological Quantum **Phase** **Transitions**

**Phases**and

**phase**

**transitions**provide an important framework to understand the physics of strongly correlated quantum many-body systems. Expand abstract.

**Phases**and

**phase**

**transitions**provide an important framework to understand the physics of strongly correlated quantum many-body systems. Topologically ordered

**phases**of matter are particularly challenging to describe, because they are characterized by long-range entanglement and go beyond the Landau-Ginzburg theory. A few tools have been developed to study topological

**phase**transitions, but the needed computations are generally demanding, they typically require the system to have particular boundary conditions, and they often provide only partial information. There is hence a high demand for developing further probes. Here, we propose to use the study of quasiparticle properties to detect

**phase**

**transitions**. Topologically ordered states support anyonic quasiparticles with special braiding properties and fractional charge. Being able to generate a given type of anyons in a system is a direct method to detect the topology, and the approach is independent from the choice of boundary conditions. We provide three examples, and for all of them we find that it is sufficient to study a relatively simple property, such as the charge of the anyons, to detect the

**phase**

**transition**point. This makes the method numerically cheap.

10/10 relevant

arXiv

Liquid-Hextic-Solid **Phase** **Transition** of a Hard-Core Lattice Gas with
Third Neighbor Exclusion

**phase**

**transitions**is obtained through direct visualization of the system at any fractional surface coverage via local bond orientation order. Expand abstract.

**phase**behavior and, in particular, the nature of

**phase**

**transitions**in two-dimensional systems is often clouded by finite size effects and by access to the appropriate thermodynamic regime. We address these issues using an alternative route to deriving the equation of state of a two-dimensional hard-core particle system, based on kinetic arguments and the Gibbs adsorption isotherm, by use of the random sequential adsorption with surface diffusion (RSAD) model. Insight into coexistence regions and

**phase**

**transitions**is obtained through direct visualization of the system at any fractional surface coverage via local bond orientation order. The analysis of the bond orientation correlation function for each individual configuration confirms that first-order

**phase**

**transition**occurs in a two-step liquid-hexatic-solid

**transition**at high surface coverage.

10/10 relevant

arXiv

Smeared **phase** **transitions** in percolation on real complex networks

**phase**

**transitions**by looking at the topological variability of the order parameter. Expand abstract.

**phase**

**transition**of percolation on real-world networks is of critical importance. Unfortunately, this

**phase**

**transition**is obfuscated by the finite size of real systems, making it hard to distinguish finite size effects from the inaccuracy of a given approach that fails to capture important structural features. Here, we borrow the perspective of smeared

**phase**

**transitions**and argue that many observed discrepancies are due to the complex structure of real networks rather than to finite size effects only. In fact, several real networks often used as benchmarks feature a smeared

**phase**

**transition**where inhomogeneities in the topological distribution of the order parameter do not vanish in the thermodynamic limit. We find that these smeared

**transitions**are sometimes better described as sequential

**phase**

**transitions**within correlated subsystems. Our results shed light not only on the nature of the percolation

**transition**in complex systems, but also provide two important insights on the numerical and analytical tools we use to study them. First, we propose a measure of local susceptibility to better detect both clean and smeared

**phase**

**transitions**by looking at the topological variability of the order parameter. Second, we highlight a shortcoming in state-of-the-art analytical approaches such as message passing, which can detect smeared

**transitions**but not characterize their nature.

10/10 relevant

arXiv

Cosmic **phase** **transitions**: their applications and experimental signatures

**phase**

**transitions**above such scales, We review different types of phase

**transition**s that can appear in our cosmic history, and their applications and experimental signatures in particular in the context of exciting gravitational waves, which could be potentially... Expand abstract.

**phase**

**transitions**are of central interest in modern cosmology. In the standard model of cosmology the Universe begins in a very hot state, right after at the end of inflation via the process of reheating/preheating, and cools to its present temperature as the Universe expands. Both new and existing physics at any scale can be responsible for catalyzing either first, second or cross over

**phase**transition, which could be either thermal or non-thermal with a potential observable imprints. Thus this field prompts a rich dialogue between gravity, particle physics and cosmology. It is all but certain that at least two cosmic

**phase**

**transitions**have occurred - the electroweak and the QCD

**phase**

**transitions**. The focus of this review will be primarily on

**phase**

**transitions**above such scales, We review different types of

**phase**

**transitions**that can appear in our cosmic history, and their applications and experimental signatures in particular in the context of exciting gravitational waves, which could be potentially be constrained by LIGO/VIRGO, Kagra, and eLISA.

10/10 relevant

arXiv

Topological **Phase** **Transition** driven by Infinitesimal Instability:
Majorana Fermions in Non-Hermitian Spintronics

**phase**

**transitions**are intriguing and fundamental cooperative phenomena in physics. Expand abstract.

**phase**

**transitions**are intriguing and fundamental cooperative phenomena in physics. Analyzing a superconducting nanowire with spin-dependent non-Hermitian hopping, we discover a topological quantum

**phase**

**transition**driven by infinitesimal cascade instability. The anomalous

**phase**

**transition**is complementary to the universal non-Bloch wave behavior of non-Hermitian systems. We show that an infinite small magnetic field drastically suppresses the non-Hermitian skin effect, inducing a topological

**phase**with Majorana boundary states. Furthermore, by identifying the bulk topological invariant, we establish the non-Hermitian bulk-boundary correspondence that does not have a Hermitian counterpart. We also discuss an experimental realization of the system by using the spin-current injection to a quantum wire.

10/10 relevant

arXiv

Squeezed light induced symmetry breaking superradiant **phase** **transition**

**phase**

**transitions**can be observed by detecting the phase space Wigner function distribution with different profiles controlled by the squeezed light intensity. Expand abstract.

**phase**

**transition**in the collective systems of qubits in a high-quality cavity, which is driven by a squeezed light. We show that the squeezed light induced symmetry breaking can result in quantum

**phase**

**transition**without the ultrastrong coupling requirement. Using the standard mean field theory, we derive the condition of the quantum

**phase**

**transition**. Surprisingly, we show that there exists a tricritical point where the first- and second-order

**phase**

**transitions**meet. With specific atom-cavity coupling strengths, both the first- and second-order

**phase**

**transition**can be controlled by the squeezed light, leading to an optical switching from the normal

**phase**to the superradiant

**phase**by just increasing the squeezed light intensity. The signature of these

**phase**

**transitions**can be observed by detecting the

**phase**space Wigner function distribution with different profiles controlled by the squeezed light intensity. Such superradiant

**phase**

**transition**can be implemented in various quantum systems, including atoms, quantum dots and ions in optical cavities as well as the circuit quantum electrodynamics system.

10/10 relevant

arXiv

Entropy production as tool for characterizing nonequilibrium **phase** **transitions**

**phase**

**transitions**can be typified in a similar way to equilibrium systems, for instance, by the use of the order parameter. However, this characterization hides the irreversible character of the dynamics as well as its influence on the

**phase**

**transition**properties. Entropy production has revealed to be an important concept for filling this gap since it vanishes identically for equilibrium systems and is positive for the nonequilibrium case. Based on distinct and general arguments, the characterization of

**phase**

**transitions**in terms of the entropy production is presented. Analysis for discontinuous and continuous

**phase**

**transitions**has been undertaken by taking regular and complex topologies within the framework of mean field theory (MFT) and beyond the MFT. A general description of entropy production portraits for $Z_2$ (``up-down'') symmetry systems under the MFT is presented. Our main result is that a given

**phase**transition, whether continuous or discontinuous has a specific entropy production hallmark. Our predictions are exemplified by an icon system, perhaps the simplest nonequilibrium model presenting an order-disorder

**phase**

**transition**and spontaneous symmetry breaking: the majority vote model. Our work paves the way to a systematic description and classification of nonequilibrium

**phase**

**transitions**through a key indicator of system irreversibility.

10/10 relevant

arXiv

**Phase** **Transitions** for the Information Bottleneck in Representation
Learning

**phase**

**transitions**in the IB objective: $\text{IB}_\beta[p(z|x)] = I(X; Z) - \beta I(Y; Z)$ defined on the encoding distribution p(z|x) for input $X$, target $Y$ and representation $Z$, where sudden jumps of $dI(Y; Z)/d \beta$ and prediction accuracy are observed with increasing $\beta$. We introduce a definition for IB

**phase**

**transitions**as a qualitative change of the IB loss landscape, and show that the

**transitions**correspond to the onset of learning new classes. Using second-order calculus of variations, we derive a formula that provides a practical condition for IB

**phase**transitions, and draw its connection with the Fisher information matrix for parameterized models. We provide two perspectives to understand the formula, revealing that each IB

**phase**

**transition**is finding a component of maximum (nonlinear) correlation between $X$ and $Y$ orthogonal to the learned representation, in close analogy with canonical-correlation analysis (CCA) in linear settings. Based on the theory, we present an algorithm for discovering

**phase**

**transition**points. Finally, we verify that our theory and algorithm accurately predict

**phase**

**transitions**in categorical datasets, predict the onset of learning new classes and class difficulty in MNIST, and predict prominent

**phase**

**transitions**in CIFAR10.

10/10 relevant

arXiv