arXiv subjects

Tihomir G. Tenev

Publications and source records attributed to Tihomir G. Tenev.

7 recordsLinked to original sources

arXiv2026

Improvement of performance of Grover's algorithm on three generations of Heron family IBM QPUs without and with topological dynamical decoupling

We investigate the performance of Grover's algorithm on three different generations of IBM Heron QPUs. On Heron family of IBM QPUs the success probabilities for three, four and five qubits without dynamical decoupling is better than results reported for previous generations of QPUs. The success probability as function of number of iterations of Grover operator is considered. A study of the improvement of results of Grover's algorithm for five qubit case with the help of topological dynamical decoupling is considered. For a six qubit case on Heron r3 QPU a clear result for finding the sought-after bitstring is reported for theoretically suboptimal number of iterations of Grover operator with the help of dynamical decoupling.

quant-ph↗

arXiv2014

Can electrostatic field lift spin degeneracy?

There are two well known mechanisms which lead to lifting of energy spin degeneracy of single electron systems - magnetic field and spin-orbit coupling. We investigate the possibility for existence of a third mechanism in which electrostatic field can lead to lifting of spin-degeneracy directly without the mediation of spin-orbit coupling. A novel argument is provided for the need of spin-orbit coupling different from the usual relativistic considerations. It is shown that due to preserved translational invariance spin splitting purely by electrostatic field is not possible for Bloch states. A possible lifting of spin degeneracy by electrostatic field characterized by broken inversion and translational invariance is considered.

quant-ph↗

arXiv2014

Rashba spin splitting in symmetric structures

It is widely believed that Rasba spin splitting occurs only in systems lacking space inversion invariance. In this letter we present analytical analysis which suggests that non-zero Rashba spin splitting occurs in systems possessing space inversion invariance. We present numerical simulations which confirm that non-zero Rashba spin splitting occurs in symmetric structures but this splitting is several orders of magnitude smaller than the Rashba spin splitting due to broken space inversion invariance.

cond-mat.mes-hall↗

arXiv2012

Spin splitting of relativistic particles in 3D

The behavior of relativistic particles in an electric and/or magnetic field is considered in the general case when the direction of propagation may differ from the direction of the field. A special attention is paid to the spin splitting and the ensuing Larmor precession frequency of both neutral and charged particles. For both neutral and charged particles, the Larmor frequency shows a longitudinal motional red shift. For a neutral particle, there is a dynamical upper bound, which depends on both the mass and the transverse momentum of the particle; moreover, the transverse motion leads to a blue shift of the Larmor frequency. For a charged particle, the longitudinal motional decrease of the spin splitting is determined by the formation of Landau levels and it has no upper limit. Unlike the nonrelativistic limit, the relativistic spin splitting depends on the Landau levels and decreases for higher Landau levels, thereby signalling the presence of a Landau ladder red shift effect.

quant-ph↗

arXiv2012

Zitterbewegung of neutral relativistic particles in static longitudinal fields

Zitterbewegung of neutral relativistic particles propagating along a constant magnetic and/or electric field is studied. It is shown that spin Zitterbewegung, when superimposed on the Larmor precession frequency, leads to a beating pattern. The existence of a forbidden frequency of spin precession is predicted. Modifications of position and velocity Zitterbewegung due to lifted spin degeneracy manifested in the appearance of longitudinal and transversal Zitterbewegung, each with two Zitterbewegung frequencies and resulting beating patterns, are reported.

quant-ph↗

arXiv2012

Relativistic effects for spin splitting of neutral particles: Upper bound and motional narrowing

We explore the properties of spin splitting for neutral particles possessing electric and magnetic dipole moments propagating in an electromagnetic field. Two notable features of the spin splitting and the associated Larmor precession are found, which are consequences of special relativity. First, we report the existence of an upper limit of spin splitting equal to twice the rest energy of the particle, and a corresponding upper limit for the Larmor precession frequency. Second, we predict the noninvariance of the spin splitting and the corresponding Larmor frequency with respect to Lorentz boosts, which bears resemblance to the classical Doppler effect.

quant-ph↗

arXiv2012

Trapped ion emulation of electric dipole moment of neutral relativistic particles

The electric dipole moments of various neutral elementary particles, such as neutron, neutrinos, certain hypothetical dark matter particles and others, are predicted to exist by the standard model of high energy physics and various extensions of it. However, the predicted values are beyond the present experimental capabilities. We propose to simulate and emulate the electric dipole moment of neutral relativistic particles and the ensuing effects in the presence of electrostatic field by emulation of an extended Dirac equation in ion traps.

quant-ph↗