arXiv subjects

Monsit Tanasittikosol

Publications and source records attributed to Monsit Tanasittikosol.

11 recordsLinked to original sources

arXiv2026

Emergent boundary-memory from unitarity constraints in a minimal two interacting quantum particles

We construct a simple model of two particles mutually attracting/repulsing in a one-dimensional lattice and investigate the corresponding dynamics. We show that enforcing reversible unitary evolution on a minimal direct-motion interaction rule necessarily gives rise to emergent boundary-memory and non-trivial dynamics. Remarkably, the resulting boundary-memory leads to event-horizon-like behaviour, entanglement between subsystem, and Page-curve-like entanglement dynamics.

quant-ph↗

arXiv2024

Spatial entanglement between two quantum walkers with exchange symmetric coins

We investigate how the initial and final exchange symmetries between the two-coin states influence the spatial entanglement dynamics between the two corresponding quantum walkers. Notably, when the initial state is anti-symmetric and the final measurement on the coins yields symmetric outcomes, all the initial entanglement will be transferred to the spatial degrees of freedom, regardless of when the coins are measured. Conversely, if the final outcomes are anti-symmetric, the spatial entanglement exhibits damped oscillation with a period ($T$) being inversely proportional to the coin operator parameter ($θ$). These behaviours are reversed for symmetric initial states. Moreover, we also observe the same spatial entanglement damping regardless of the initial state when the post-selected results lack symmetry. Our findings reveal how symmetries affect the entanglement dynamics in quantum walks, offering potential insights for applications in quantum technology.

quant-ph↗

arXiv2023

Vacuum stability of phantom field from the nonuniqueness of Lagrangian

According to the nonuniqueness principle, the homogeneous scalar field Lagrangian can be expressed in various forms both standard and nonstandard ones. Therefore, the standard and all possible nonstandard Lagrangians can be linearly combined while the Klein-Gordon equation is still intact. This linear combination of Lagrangians is used to demonstrate that the energy density of homogeneous phantom field can possibly be bounded from below. The applications of this new Lagrangian in the nature of the ghost condensate and the equation of state with $w<-1$ are discussed.

hep-th↗

arXiv2023

The non-standard Lagrangian from non-uniqueness principle of the real scalar field and fermion field

We construct the non-standard Lagrangian, called the multiplicative form, of the homogeneous scalar field and fermion field through the inverse calculus of variations, which the equation of motion still satisfies the Klein-Gordon and Dirac equations, respectively. By employing the non-uniqueness of Lagrangian, we show that the Lagrangians can be written between the linear combination of standard and non-standard Lagrangian. The stability of the ghost field, an unnatural smallness of cosmological constant, and the chiral condensate are discussed by applying these new Lagrangians.

hep-th↗

arXiv2022

The Natural TeV Cutoff of the Higgs Field from the Multiplicative Lagrangian

The various types of the non-standard Lagrangian can be added to the standard Lagrangian with the invariant of the equation of motion in the low energy limit. In this paper, we construct the multiplicative Lagrangian of a complex scalar field giving the approximated Klein-Gordon equation from the inverse problem of the calculus of variation. Then, this multiplicative Lagrangian with arbitrary high cutoff is applied to the toy model of the Higgs mechanism in U(1)-gauge symmetry in order to study the simple effects in the Higgs physics. We show that, after spontaneous symmetry breaking happens, the Higgs vev is free from the Fermi-coupling constant and the Higgs field gets the natural cutoff in TeV scale. The other relevant coupling constants, the UV-sensitivity of Higgs mass due to the loop correction, some applications on the strong CP problem as well as anomalous small fermion mass, and the cosmological constant problem are also discussed.

hep-th↗

arXiv2022

The Higgs mechanism from the effective theory of the non-minimal gravity action

The spontaneous symmetry breaking for the massless scalar field naturally arises from the framework of the effective theory (the non-minimal coupling of gravity to a scalar field). A magic key ingredient is to add the large vacuum energy density, contributing to the cosmological constant, to the Lagrangian density. By applying this modified spontaneous symmetry breaking with the gauge theory (called modified Higgs mechanism), the inflation physics and the electroweak phase transition can be generated from the same framework. However, this comes with the huge price-the large cosmological constant which is known as the dark energy problem. The possible solution of this issue is also discussed.

hep-ph↗

arXiv2017

Ground state entanglement entropy for discrete-time two coupled harmonic oscillators

The ground state entanglement of the system, both in discrete-time and continuous-time cases, is quantified through the linear entropy. The result shows that the entanglement increases as the interaction between the particles increases in both time scales. It is also found that the strength of the harmonic potential affects the formation rate of the entanglement of the system. The different feature of the entanglement between continuous-time and discrete-time scales is that, for discrete-time entanglement, there is a cut-off condition. This condition implies that the system can never be in a maximally entangled state.

math-ph↗

arXiv2016

On the multiplicative form of the Lagrangian

An alternative class of the Lagrangian called the multiplicative form is suc- cessfully derived for a system with one degree of freedom for both non-relativistic and relativistic cases. This new Lagrangian can be considered as a 1-parameter: λ extended class from the standard additive form of the Lagrangian since both yield the same equation of motion. Remarkably, the multiplicative form of the Lagrangian could be treated as a generating function to produce an infinite hierar- chy of Lagrangians which give the same equation of motion. This nontrivial set of Lagrangians confirms that indeed Lagrange function is not unique.

math-ph↗

arXiv2016

On the Lagrangian 1-Form Structure of the Hyperbolic Calogero-Moser System

In this work, we present another example of the Lagrangian 1-form structure for the hy- perbolic Calogero-Moser system both in discrete-time level and continuous-time level. The discrete-time hyperbolic Calogero-Moser system is obtained by considering pole-reduction of the semi-discrete Kadomtsev-Petviashvili (KP) equation. The key relation called the discrete-time closure relation is directly obtained from the compatibility between the temporal Lax matrices. The continuous-time hierarchy of the hyperbolic Calogero-Moser system is obtained through two successive continuum limits. The continuous-time closure relation, which is a consequence of continuum limits on the discrete-time one, is also shown to hold.

nlin.SI↗

arXiv2014

On the Lagrangian structure of Calogero's Goldfish model

The discrete-time rational Calogero's goldfish system is obtained from the Ansatz Lax pair. The discrete-time Lagrangians of the system possess the discrete-time 1-form structure as those in the discrete-time Calogero-Moser system and discrete-time Ruijsenaars-Schneider system. Performing two steps of continuum limits, we obtain Lagrangian hierarchy for the system. Expectingly, the continuous-time Lagrange 1-form structure of the system holds. Furthermore, the connection to the lattice KP systems is also established.

nlin.SI↗

arXiv2012

Three-photon electromagnetically induced transparency using Rydberg states

We demonstrate electromagnetically induced transparency (EIT) in a four-level cascade system where the upper level is a Rydberg state. The observed spectral features are sub-Doppler and can be enhanced due to the compensation of Doppler shifts with AC Stark shifts. A theoretical description of the system is developed which agrees well with the experimental results and an expression for the optimum parameters is derived.

physics.atom-ph↗