arXiv subjects

Sérgio Ricardo Muniz

Publications and source records attributed to Sérgio Ricardo Muniz.

6 recordsLinked to original sources

arXiv2026

Benchmark of the Schmiedl-Seifert optimal protocol with reduced dissipated work and fluctuations in optical tweezers

Finite-time thermodynamic transformations generally dissipate energy, as required by the Second Law, so identifying and investigating energetically optimal processes remain relevant for understanding and designing efficient thermal devices. In this context, we present here a systematic experimental benchmark of the finite-time minimum-work compression protocol derived by Schmiedl and Seifert for an overdamped Brownian particle in a harmonic trap. By parametrically controlling the trap stiffness, we compare the full work statistics of the analytical optimal protocol with those obtained under linear driving across a broad range of protocol durations and amplitudes. We find that the optimal protocol consistently reduces both the mean work and the work variance relative to linear driving. Although the Schmiedl-Seifert protocol was primarily derived to minimize the mean work, our data show, in the present setting, a clear reduction in fluctuations and high-work tails under realistic bandwidth-limited actuation. This observation connects our benchmark to the growing interest in higher-order cumulants and to current developments in stochastic-thermodynamic control.

cond-mat.soft↗

arXiv2022

Spin coherence mapping of NV centers in diamond

In recent years, nitrogen-vacancy (NV) color centers in diamond have become excellent solid-state quantum sensors due to their electronic spin properties. Especially for their easy optical initialization and detection, together with their very large spin coherence at room temperature. Many studies have reported their use for sensing temperature, strain, electric fields, and mainly magnetic fields. Here, we show how to build a two-dimensional map of the electronic spin coherence of an ensemble of NV centers in ultra-pure diamond, using an optical imaging protocol combined with microwave pulses relying simply on a regular CCD camera.

quant-ph↗

arXiv2022

Measurements of spin-coherence in NV centers for diamond-based quantum sensors

One of the biggest challenges to implement quantum protocols and quantum information processing (QIP) is achieving long coherence times, usually requiring systems at ultra-low temperatures. The nitrogen-vacancy (NV) center in diamond is a promising alternative to this problem. Due to its spin properties, easy manipulation, and the possibility of doing optical state initialization and readout, it quickly became one of the best solid-state spin systems for QIP at room temperature. Here, we present the characterization of the spin-coherence of an ensemble of NV centers in an engineered sample of ultrapure diamond as a testbed for quantum protocols for quantum metrology.

quant-ph↗

arXiv2022

Diamond-based optical vector magnetometer

We describe here the construction and characterization of a high-resolution optical magnetometer to measure the full vector magnetic field on an ultrathin layer near the surface of the device. This solid-state device is based on quantum sensors created by a layer of nitrogen-vacancy (NV) centers less than 20 nm below the surface of an ultrapure diamond. This ensemble of nanosensors provides a versatile device capable of mapping magnetic fields and surface current densities with a sub-micrometer resolution and high sensitivity, making it suitable for many applications. Here, we show a custom-built prototype to demonstrate an operating proof-of-concept device.

quant-ph↗

arXiv2022

Generating arbitrary laser beam shapes through phase-mapped designed beam splitting

We describe here a method to generate high-definition arbitrary laser beam shapes and profiles useful to many applications, ranging from optical patterning and lithography to optical trapping of microscopic particles and ultracold atoms. The phase contrast between a binary grating and a targeted intensity distribution is encoded on a spatial light modulator to control light diffraction, producing very sharp, speckles-free, and smooth images. Besides simplicity, not requiring additional phase-plates, the method provides straightforward encoding of images onto phase-only masks by a direct pixel mapping, allowing simpler feedback schemes to correct and control light distributions and optical potentials in real-time.

physics.optics↗

arXiv2022

Dynamically controlled double-well optical potential for colloidal particles

This preliminary study presents a simple modulation scheme to dynamically create time-averaged optical potentials to trap colloidal particles using acousto-optical modulation. The method provides access to control experimentally relevant parameters of a tunable double-well potential. We show experimental data successfully adjusting the trapping distance in the range 20-2000 nm and discuss situations arising when reconstructing time-averaged optical potentials from trapped particle data. This is the first step towards studying colloidal particles in dynamically modulated optical potentials to explore the stochastic thermodynamics of mesoscopic systems and small-scale thermo-mechanical machines.

cond-mat.soft↗