arXiv subjects

Philip Caesar M. Flores

Publications and source records attributed to Philip Caesar M. Flores.

7 recordsLinked to original sources

arXiv2026

Enantiosensitive molecular compass

Chirality describes the asymmetry between an object and its mirror image and underlies diverse functionalities across molecular, mesoscopic and bulk matter. A particularly intriguing example is chirality-induced spin selectivity (CISS), where chiral structures generate enantio-sensitive spin polarization. Despite extensive research, its microscopic origin and unexpectedly large magnitude remain unresolved. Here, we isolate the intrinsic coupling between chirality and spin by considering spin-resolved photoionization of randomly oriented chiral molecules under isotropic illumination. We show that electric-dipole photoionization in the presence of spin-orbit coupling generates intrinsic correlations between molecular orientation and photoelectron spin that survive complete isotropic averaging. We identify these spin-orientation correlations as the microscopic origin of CISS in photoionization and reveal their complementary manifestation: selecting the photoelectron spin orients the residual molecular ensemble, realizing spin-orientation locking, whereas selecting molecular orientation produces CISS. Both effects are governed by the same correlation strength, set by the magnitude of a molecular-frame photoionization Bloch vector that defines an enantio-sensitive molecular compass. An analogous compass emerges in photoexcitation. Our results establish spin - orientation correlations as a fundamental ingredient of chiral spin photodynamics and provide a microscopic framework for understanding and exploiting spin selectivity in chiral matter.

cond-mat.mes-hall↗

arXiv2026

Spin-current correlations in photoionization of chiral molecules

Chirality-induced spin selectivity (CISS) refers to phenomena where molecular chirality governs spin polarization. While symmetry simply requires chiral molecules to support spin-vector correlations, we show that CISS is fundamentally a conditioned measurement of these correlations. We illustrate this principle for spin-resolved one-photon ionization of a randomly oriented ensemble of chiral molecules. We introduce and quantify the phenomenon of enantio-sensitive locking of the photoelectron current to its spin, thereby providing a complete description of spin-conditioned photoelectron currents in one-photon ionization.

quant-ph↗

arXiv2026

Geometric mechanisms enabling spin- and enantio-sensitive observables in one photon ionization of chiral molecules

We examine spin-resolved photoionization of randomly oriented chiral molecules via circularly polarized light, and revisit earlier predictions of Cherepkov (J. Phys. B: Atom. Mol. Phys. 16, 1543, 1983). We will show that the dynamical origin of spin- and enantio-sensitive observables arise from two intrinsic mechanisms that are quantified by two pseudovectors stemming from the geometric properties of the photoionization dipoles in spin space and in real space, and an extrinsic mechanism which is a directional bias introduced by the well-defined direction of light polarization. These mechanisms arise solely from electric dipole interactions. Consequently, this means that the ten independent parameters that was earlier predicted by Cherepkov to fully describe spin-resolved photoionization of chiral molecules can be reduced as moments of these three pseudovectors. We also find that the molecular pseudoscalars describing the spin- and enantio-sensitive components of the yield can be described by the flux of these pseudovectors through the energy shell, which changes sign upon switching enantiomers. Our results provide compact expressions for these observables which provide an intuitive picture on what determines the strength of these spin- and enantio-sensitive observables. The approach can be readily generalized to photoexcitation, multiphoton processes, and arbitrary field polarizations. Regardless of the specific driving conditions, the resulting spin- and enantio-sensitive observables are still controlled by the same three pseudovectors, underscoring their universal role as the primary generators of chirality-induced spin asymmetries, emphasizing their fundamental geometric origin and the universality of the mechanism identified here.

physics.atom-ph↗

arXiv2024

Partial and full tunneling processes across potential barriers

We introduce the concept of partial and full tunneling processes to explain the seemingly contradictory non-zero and vanishing tunneling times often reported in the literature. Our analysis starts by considering the traversal time of a quantum particle through a potential barrier, including both above and below-barrier traversals, using the theory of time-of-arrival operators. We then show that there are three traversal processes corresponding to non-tunneling, full-tunneling, and partial tunneling. The distinction between the three depends on the support of the incident wavepackets energy distribution in relation to the shape of the barrier. Non-tunneling happens when the energy distribution of the quantum particle lies above the maximum of the potential barrier. Otherwise, full-tunneling process occurs when the energy distribution of the particle is below the minimum of the potential barrier. For this process, the obtained traversal time is interpreted as the tunneling time. Finally, the partial-tunneling process occurs when the energy distribution lies between the minimum and maximum of the potential barrier. This signifies that the quantum particle tunneled only through some portions of the potential barrier. We argue that the duration for a partial-tunneling process should not be interpreted as the tunneling time but instead as a partial traversal time to differentiate it from the full-tunneling process. We then show that a full-tunneling process is always instantaneous, while a partial-tunneling process takes a non-zero amount of time. We are then led to the hypothesis that experimentally measured non-zero and vanishing tunneling times correspond to partial and full-tunneling processes, respectively.

quant-ph↗

arXiv2022

Relativistic free motion time of arrival operator for massive spin-0 particles with positive energy

A relativistic version of the Aharonov-Bohm time of arrival operator for spin-0 particles was constructed by Razavi in [Il Nuovo Cimento B \textbf{63}, 271 (1969)]. We study the operator in detail by taking its rigged Hilbert space extension. It is shown that the rigged Hilbert space extension of the operator provides more insights into the time of arrival problem that goes beyond Razavi's original results. This allows us to use time of arrival eigenfunctions that exhibit unitary arrival to construct time of arrival distributions. The expectation value is also calculated and shown that particles can arrive earlier or later than expected classically. Lastly, the constructed time of arrival distribution, and expectation value are shown to be consistent with special relativity.

quant-ph↗

arXiv2019

Quantum free fall motion and quantum violation of weak equivalence principle

The weak equivalence principle (WEP) in the quantum regime has been the subject of many studies with a broad range of approach to the problem. Here we tackle the problem anew through the time of arrival (TOA) operator approach by constructing the time of arrival operator for a non-relativistic and structureless particle that is projected upward in a uniform gravitational field with an intended arrival point below the classical turning point. The TOA-operator is constructed under the constraint that the inertial and gravitational masses are equivalent, and that Galilean invariance is preserved. These constraints are implemented by Weyl-quantization of the corresponding classical time of arrival function for the projectile. The expectation value of the TOA-operator is explicitly shown to be equal to the classical time of arrival plus mass-dependent quantum correction terms, implying incompatibility of the weak equivalence principle with quantum mechanics. The full extent of the violation of the WEP is shown through the mass dependence of time of arrival distribution for the projectile.

quant-ph↗

arXiv2016

Synchronizing quantum and classical clocks made of quantum particles

We demonstrate that the quantum corrections to the classical arrival time for a quantum object in a potential free region of space, as computed by Galapon [Phys. Rev. A {\bf 80}, 030102(R) (2009)], can be eliminated up to a given order of $\hbar$ by choosing an appropriate position-dependent phase for the object's wavefunction. This then implies that we can make the quantum arrival time of the object as close as possible to its corresponding classical arrival time, allowing us to synchronize a classical and quantum clock which tells time using the classical and quantum arrival time of the object, respectively. We provide an example for synchronizing such a clock by making use of a quantum object with a position-dependent phase imprinted on the object's initial wavefunction with the use of an impulsive potential.

quant-ph↗