Abstract We use the spread complexity (SC) of a time-evolved state after sudden quantum quench in Lipkin–Meshkov–Glick (LMG) model prepared ground as probe phase transition when system is quenched toward critical point. By studying growth effective number elements Krylov basis that contributes to SC more than preassigned cutoff, we show how two phases LMG can be distinguished. also explore time evolution entropy both non-critical and quenches. sum contributing converges slowly symmetric...

A bstract Using spread complexity and entropy, we study non-unitary quantum dynamics. For non-hermitian Hamiltonians, extend the bi-Lanczos construction for Krylov basis to Schrödinger picture. Moreover, implement an algorithm adapted complex symmetric Hamiltonians. This reduces computational memory requirements by half compared construction. We apply this one-dimensional tight-binding Hamiltonian subject repeated measurements at fixed small time intervals, resulting in effective find that...

This study investigates the behavior of wave functions in parity-time (\ensuremath{\mathcal{P}}\ensuremath{\mathcal{T}}) symmetric quantum systems, focusing on their spread and localization. Using a tight-binding chain model, authors explore dynamics under \ensuremath{\mathcal{P}}\ensuremath{\mathcal{T}} symmetry its breaking. By employing innovative information measures, such as complexity, entropy, inverse participation ratio Krylov space, they quantify function's distribution. In...

Abstract The Raman spectra of KHSO 4 single crystals in different geometries have been investigated the 10–4000 cm −1 range at 300 K, 150 K and 120 K. infrared polycrystalline also measured. An interpretation these results consistent with crystal structure other information on this system is presented.

We evaluate out of time ordered correlators in certain low dimensional quantum systems at zero temperature, subjected to homogenous quenches. find that when the Lyapunov exponent exists, it can be identified with quenched energy. show naturally gets related post-quench effective temperature. In context sudden quenches is determined terms quench amplitude while for smooth we observe scalings (both Kibble-Zurek as well fast) rate. The are identical energy generated during quench.

We globally quench the theory of two dimensional massless fermions (many flavours) with quartic interactions by making coupling a smooth function time. Working in derivative expansion we show that discrete Z2 symmetry case Gross-Neveu model, and U(1) Nambu-Jona-Lasinio are restored during zero-temperature quench. For model this can be understood as an effective thermalization. The time restoration shows scaling rate. identify Kibble-Zurek problem. In suitable double limit, may terms...

We use the spread complexity of a time evolved state after sudden quantum quench in Lipkin-Meshkov-Glick (LMG) model prepared ground as probe phase transition when system is quenched towards critical point. By studying growth effective number elements Krylov basis, those contribute to more than preassigned cut off, we show how two phases LMG can be distinguished. also explore evolution entropy both non-critical and quenches. that sum contributing converges slowly symmetric compared broken...

We present a framework for investigating wave function spreading in $\mathcal{PT}$-symmetric quantum systems using spread complexity and entropy. consider tight-binding chain with complex on-site potentials at the boundary sites. In $\mathcal{PT}$-unbroken phase, is delocalized. find that $\mathcal{PT}$-broken it becomes localized on one edge of lattice. This localization realization non-Hermitian skin effect. Localization phase observed both lattice basis Krylov basis. Spread entropy,...

Using spread complexity and entropy, we study non-unitary quantum dynamics. For non-hermitian Hamiltonians, extend the bi-Lanczos construction for Krylov basis to Schr\"odinger picture. Moreover, implement an algorithm adapted complex symmetric Hamiltonians. This reduces computational memory requirements by half compared construction. We apply this one-dimensional tight-binding Hamiltonian subject repeated measurements at fixed small time intervals, resulting in effective find that initially...

We evaluate out of time ordered correlators in certain low dimensional quantum systems at zero temperature, subjected to homogenous quenches. find that when the Lyapunov exponent exists, it can be identified with quenched energy. show naturally gets related post-quench effective temperature. In context sudden quenches is determined terms quench amplitude while for smooth we observe scalings (both Kibble-Zurek as well fast) rate. The are identical energy generated during quench.

We work perturbatively with an interacting quantum field theory comprised of two distinct scalar fields. In this theory, we introduce a sudden quench the mass one scalars at time $t_0$. Also, quartic interaction between is turned on $t_{in}$. These break time-translation invariance. setup examine effects relative ordering $t_0$ and $t_{in}$ composite operator mixing. study how such mixing affect features potential. find that late effective potential can be sensitive enough to quenches...