arXiv subjects

A. Tobalina

Publications and source records attributed to A. Tobalina.

11 recordsLinked to original sources

arXiv2026

Invariant-based inverse engineering for balanced displacement of a cart-pole system

Adiabaticity is a key concept in physics, but its applications in mechanical and control engineering remain underexplored. Adiabatic invariants ensure robust dynamics under slow changes, but they impose impractical time limitations. Shortcuts to Adiabaticity (STA) overcome these limitations by enabling fast operations with minimal final excitations. In this work, we set a STA strategy based on dynamical invariants and inverse engineering to design the trajectory of a cart-pole, a system characterized by its instability and repulsive potential. The trajectories found guarantee a balanced transport of the cart-pole within the small oscillations regime. The results are compared to numerical simulations with the exact non-linear model to set the working domain of the designed protocol.

physics.class-ph↗

arXiv2023

High-Resolution NMR Spectroscopy at Large Fields with Nitrogen Vacancy Centers

Ensembles of nitrogen-vacancy (NV) centers are used as sensors to detect NMR signals from micron-sized samples at room temperature. In this scenario, the regime of large magnetic fields is especially interesting as it leads to a large nuclear thermal polarisation -- thus, to a strong sensor response even in low concentration samples -- while chemical shifts and J-couplings become more accessible. Nevertheless, this regime remains largely unexplored owing to the difficulties to couple NV-based sensors with high-frequency nuclear signals. In this work, we circumvent this problem with a method that maps the relevant energy shifts in the amplitude of an induced nuclear spin signal that is subsequently transferred to the sensor. This stage is interspersed with free-precession periods of the sample nuclear spins where the sensor does not participate. Thus, our method leads to high spectral resolutions ultimately limited by the coherence of the nuclear spin signal.

quant-ph↗

arXiv2021

Tailored Ion Beam for Precise Color Center Creation

We present a unitary quantum control scheme that produces a highly monochromatic ion beam from a Paul trap. Our protocol is implementable by supplying the segmented electrodes with voltages of the order of Volts, which mitigates the impact of fluctuating voltages in previous designs and leads to a low-dispersion beam of ions. Moreover, our proposal does not rely on sympathetically cooling the ions, which bypasses the need of loading different species in the trap -- namely, the propelled ion and, e.g., a $^{40}$Ca$^+$ atom able to exert sympathetic cooling -- incrementing the repetition rate of the launching procedure. Our scheme is based on an invariant operator linear in position and momentum, which enables us to control the average extraction energy and the outgoing momentum spread. In addition, we propose a sequential operation to tailor the transversal properties of the beam before the ejection to minimize the impact spot and to increase the lateral resolution of the implantation.

quant-ph↗

arXiv2020

Invariant-based inverse engineering of time-dependent, coupled harmonic oscillators

Two-dimensional systems with time-dependent controls admit a quadratic Hamiltonian modelling near potential minima. Independent, dynamical normal modes facilitate inverse Hamiltonian engineering to control the system dynamics, but some systems are not separable into independent modes by a point transformation. For these "coupled systems" 2D invariants may still guide the Hamiltonian design. The theory to perform the inversion and two application examples are provided: (i) We control the deflection of wave packets in transversally harmonic waveguides; and (ii) we design the state transfer from one coupled oscillator to another.

quant-ph↗

arXiv2020

Time-dependent harmonic potentials for momentum or position scaling

Cooling methods and particle slowers as well as accelerators are basic tools for fundamental research and applications in different fields and systems. We put forward a generic mechanism to scale the momentum of a particle, regardless of its initial position and momentum, by means of a transient harmonic potential. The design of the time-dependent frequency makes use of a linear invariant and inverse techniques drawn from ''shortcuts to adiabaticity''. The timing of the process may be decided beforehand and its influence on the system evolution and final features is analyzed. We address quantum systems but the protocols found are also valid for classical particles. Similar processes are possible as well for position scaling.

quant-ph↗

arXiv2019

Invariant-based inverse engineering for fast and robust load transport in a double pendulum bridge crane

We set a shortcut-to-adiabaticity strategy to design the trolley motion in a double-pendulum bridge crane. The trajectories found guarantee payload transport without residual excitation regardless of the initial conditions within the small oscillations regime. The results are compared with exact dynamics to set the working domain of the approach. The method is free from instabilities due boundary effects or to resonances with the two natural frequencies.

physics.class-ph↗

arXiv2019

Fast state and trap rotation of a particle in an anisotropic potential

We study the dynamics of a quantum or classical particle in a two-dimensional rotating anisotropic harmonic potential. By a sequence of symplectic transformations for constant rotation velocity we find uncoupled normal generalized coordinates and conjugate momenta in which the Hamiltonian takes the form of two independent harmonic oscillators. The decomposition into normal-mode dynamics enables us to design fast trap-rotation processes to produce a rotated version of an arbitrary initial state, when the two normal frequencies are commensurate.

quant-ph↗

arXiv2018

Energy consumption for ion transport in a segmented Paul trap

There is recent interest in determining energy costs of shortcuts to adiabaticity (STA), but different definitions of "cost" have been used. We demonstrate the importance of taking into account the Control System (CS) for a fair assessment of energy flows and consumptions. We model the energy consumption and power to transport an ion by a STA protocol in a multisegmented Paul trap. The ion is driven by an externally controlled, moving harmonic oscillator. Even if no net ion- energy is gained at destination, setting the time-dependent control parameters is a macroscopic operation that costs energy and results in energy dissipation for the short time scales implied by the intrinsically fast STA processes. The potential minimum is displaced by modulating the voltages on control (dc) electrodes. A secondary effect of the modulation, usually ignored as it does not affect the ion dynamics, is the time- dependent energy shift of the potential minimum. The non trivial part of the energy consumption is due to the electromotive forces to set the electrode voltages through the low-pass filters required to preserve the electronic noise from decohering the ion's motion. The results for the macroscopic CS (the Paul trap) are compared to the microscopic power and energy of the ion alone. Similarities are found -and may be used quantitatively to minimize costs- only when the CS-dependent energy shift of the harmonic oscillator is included in the ion energy.

quant-ph↗

arXiv2017

Invariant-based inverse engineering of crane control parameters

By applying invariant-based inverse engineering in the small-oscillations regime, we design the time dependence of the control parameters of an overhead crane (trolley displacement and rope length), to transport a load between two positions at different heights with minimal final energy excitation for a microcanonical ensemble of initial conditions. The analogies between ion transport in multisegmented traps or neutral atom transport in moving optical lattices and load manipulation by cranes opens a route for a useful transfer of techniques among very different fields.

quant-ph↗

arXiv2017

Energy consumption for Shortcuts To Adiabaticity

Shortcuts to adiabaticity let a system reach the results of a slow adiabatic process in a shorter time. We propose to quantify the "energy cost" of the shortcut by the energy consumption of the system enlarged by including the control device. A mechanical model where the dynamics of the system and control device can be explicitly described illustrates that a broad range of possible values for the consumption are possible, including zero (above the adiabatic energy increment) when friction is negligible and the energy given away as negative power is stored and recovered by perfect regenerative braking.

quant-ph↗

arXiv2017

Fast atom transport and launching in a nonrigid trap

We study the shuttling of an atom in a trap with controllable position and frequency. Using invariant-based inverse engineering, protocols in which the trap is simultaneously displaced and expanded are proposed to speed up transport between stationary trap locations as well as launching processes with narrow final-velocity distributions. Depending on the physical constraints imposed, either simultaneous or sequential approaches may be faster. We consider first a perfectly harmonic trap, and then extend the treatment to generic traps. Finally, we apply this general framework to a double-well potential to separate different motional states with different launching velocities.

quant-ph↗