arXiv subjects

Benjamin A. Stickler

Publications and source records attributed to Benjamin A. Stickler.

At least 37 records · Page 2Linked to original sources

arXiv2023

Spin Read-out of the Motion of Levitated Electrically Rotated Diamonds

Recent advancements with trapped nano- and micro-particles have enabled the exploration of motional states on unprecedented scales. Rotational degrees of freedom stand out due to their intrinsic non-linearity and their coupling with internal spin degrees of freedom, opening up possibilities for gyroscopy and magnetometry applications and the creation of macroscopic quantum superpositions. However, current techniques for fast and reliable rotation of particles with internal spins face challenges, such as optical absorption and heating issues. Here, to address this gap, we demonstrate electrically driven rotation of micro-particles levitating in Paul traps. We show that micro-particles can be set to rotate stably at 150,000 rpm by operating in a hitherto unexplored parametrically driven regime using the particle electric quadrupolar moment. Moreover, the spin states of nitrogen-vacancy centers in diamonds undergoing full rotation were successfully controlled, allowing accurate angular trajectory reconstruction and demonstrating high rotational stability over extended periods. These achievements mark progress toward interfacing full rotation with internal magnetic degrees of freedom in micron-scale objects. In particular, it extends significantly the type of particles that can be rotated, such as ferromagnets, which offers direct implications for the study of large gyromagnetic effects at the micro-scale.

quant-ph↗

arXiv2023

Force-Gradient Sensing and Entanglement via Feedback Cooling of Interacting Nanoparticles

We show theoretically that feedback-cooling of two levitated, interacting nanoparticles enables differential sensing of forces and the observation of stationary entanglement. The feedback drives the two particles into a stationary, non-thermal state which is susceptible to inhomogeneous force fields and which exhibits entanglement for sufficiently strong inter-particle couplings. We predict that force-gradient sensing at the zepto-Newton per micron range is feasible and that entanglement due to the Coulomb interaction between charged particles can be realistically observed in state-of-the-art setups.

quant-ph↗

arXiv2023

Amplifying a zeptonewton force with a single-ion nonlinear oscillator

Nonlinear mechanical resonators display rich and complex dynamics and are important in many areas of fundamental and applied sciences. In this letter, we show that a particle confined in a funnel-shaped potential features a Duffing-type nonlinearity due to the coupling between its radial and axial motion. Employing an ion trap platform, we study the nonlinear oscillation, bifurcation and hysteresis of a single calcium ion driven by radiation pressure. Harnessing the bistability of this atomic oscillator, we demonstrate a 20-fold enhancement of the signal from a zeptonewton-magnitude harmonic force through the effect of vibrational resonance. Our findings open up a range of possibilities for controlling and exploiting nonlinear phenomena of mechanical oscillators close to the quantum regime.

quant-ph↗

arXiv2022

Spin-Controlled Quantum Interference of Levitated Nanorotors

We describe how to prepare an electrically levitated nanodiamond in a superposition of orientations via microwave driving of a single embedded nitrogen-vacancy (NV) center. Suitably aligning the magnetic field with the NV center can serve to reach the regime of ultrastrong coupling between the NV and the diamond rotation, enabling single-spin control of the particle's three-dimensional orientation. We derive the effective spin-oscillator Hamiltonian for small amplitude rotation about the equilibrium configuration and develop a protocol to create and observe quantum superpositions of the particle orientation. We discuss the impact of decoherence and argue that our proposal can be realistically implemented with near-future technology.

quant-ph↗

arXiv2022

Surface-induced decoherence and heating of charged particles

Levitating charged particles in ultra-high vacuum provides a preeminent platform for quantum information processing, for quantum-enhanced force and torque sensing, for probing physics beyond the standard model, and for high-mass tests of the quantum superposition principle. Existing setups range from single atomic ions, to ion chains and crystals, to charged molecules and nanoparticles. Future technological applications of such quantum systems will be crucially affected by fluctuating electric fields emanating from nearby electrodes, which interact with the levitated particles' monopole and higher charge moments. In this article, we provide a theoretical toolbox for describing how the rotational and translational quantum dynamics of charged nano- to microscale objects is affected by near metallic and dielectric surfaces, as characterized by their macroscopic dielectric response. The resulting quantum master equations describe the coherent surface-particle interaction, due to image charges and Casimir-Polder potentials, as well as surface-induced decoherence and heating, with the experimentally observed frequency and distance scaling. We explicitly evaluate the master equations for typical charge distributions and types of motion, thereby providing the tools required for describing and mitigating surface-induced decoherence in a variety of experiments with charged objects.

quant-ph↗

arXiv2022

Observation of strong and tunable light-induced dipole-dipole interactions between optically levitated nanoparticles

Arrays of optically trapped nanoparticles have emerged as a promising platform for the study of complex non-equilibrium phenomena. Analogous to atomic many-body systems, one of the crucial ingredients is the ability to precisely control the interactions between particles. However, the optical interactions studied thus far only provide conservative optical binding forces of limited tunability. Here we demonstrate a coupling mechanism that is orders of magnitude stronger and has new qualitative features. These effects arise from the previously unexplored phase coherence between the optical fields that drive the light-induced dipole-dipole interaction. In addition, polarization control allows us to observe electrostatic coupling between charged particles in the array. Our results pave the way for a fully programmable many-body system of interacting nanoparticles with tunable dissipative and nonreciprocal interactions, which are instrumental for exploring entanglement and topological phases in arrays of levitated nanoparticles.

physics.optics↗

arXiv2022

Interferometric control of nanorotor alignment

The intrinsically non-linear rotation dynamics of rigid bodies offer unprecedented ways to exploit their quantum motion. In this Letter we devise a rotational analog of Mach-Zehnder interferometry, which allows steering symmetric rotors from fully aligned to completely antialigned. The scheme uses a superposition of four distinct orientations, emerging at the eighth of the quantum revival time, whose interference can be controlled by a weak laser pulse. We develop a semiclassical model of the effect and demonstrate that it persists even in presence of imperfections and decoherence.

quant-ph↗

arXiv2022

MAQRO -- BPS 2023 Research Campaign Whitepaper

The objective of the proposed MAQRO mission is to harness space for achieving long free-fall times, extreme vacuum, nano-gravity, and cryogenic temperatures to test the foundations of physics in macroscopic quantum experiments. This will result in the development of novel quantum sensors and a means to probe the foundations of quantum physics at the interface with gravity. Earlier studies showed that the proposal is feasible but that several critical challenges remain, and key technologies need to be developed. These new technologies will open up the potential for achieving additional science objectives. The proposed research campaign aims to advance the state of the art and to perform the first macroscopic quantum experiments in space. Experiments on the ground, in micro-gravity, and in space will drive the proposed research campaign during the current decade to enable the implementation of MAQRO within the subsequent decade.

quant-ph↗

arXiv2021

Torque-free manipulation of nanoparticle rotations via embedded spins

Spin angular momentum and mechanical rotation both contribute to the total angular momentum of rigid bodies, leading to spin-rotational coupling via the Einstein-de Haas and Barnett effects. Here we show that the revolutions of symmetric nanorotors can be strongly affected by a small number of intrinsic spins. The resulting dynamics are observable with freely rotating nanodiamonds with embedded nitrogen-vacancy centers and persist for realistically-shaped near-symmetric particles, opening the door to torque-free schemes to control their rotations at the quantum level.

quant-ph↗

arXiv2021

Electric trapping and circuit cooling of charged nanorotors

The motion of charged particles can be interfaced with electric circuitry via the current induced in nearby pick-up electrodes. Here we show how the rotational and translational dynamics of levitated objects with arbitrary charge distributions can be coupled to a circuit and how the latter acts back on the particle motion. The ensuing cooling rates in series and parallel RLC circuits are determined, demonstrating that quadrupole ion traps are well suited for implementing all-electric cooling. We derive the effective macromotion potential for general trap geometries and demonstrate numerically how consecutive rotational and translational resistive cooling of a microscale particle can be achieved in linear Paul traps.

quant-ph↗

arXiv2021

Talbot self-imaging and two-photon interference in ring-core fibers

Wave propagation on the surface of cylinders exhibits interferometric self imaging, much like the Talbot effect in the near-field diffraction at periodic gratings. We report the experimental observation of the cylindrical Talbot carpet in weakly-guiding ring-core fibers for classical light fields. We further show that the ring-core fiber acts as a high-order optical beamsplitter for single photons, whose output can be controlled by the relative phase between the input light fields. By also demonstrating high-quality two-photon interference between indistinguishable photons sent into the ring-core fiber, our findings open the door to applications in optical telecommunications as a compact beam multiplexer as well as in quantum information processing tasks as a scalable realization of a linear optical network.

physics.optics↗

arXiv2021

Theory of nanoparticle cooling by elliptic coherent scattering

Coherent scattering of an elliptically polarised tweezer into a cavity mode provides a promising platform for cooling levitated nanoparticles into their combined rotational and translational quantum regime [Phys. Rev. Lett. 126, 163603 (2021)]. This article presents the theory of how aspherical nanoparticles are affected by elliptically polarised laser beams, how two orthogonal cavity modes enable rotational and translational cooling, and how the resulting power spectra contain signatures of rotational non-linearities. We provide analytic expressions for the resulting trapping frequencies, opto-mechanical coupling strengths, cooling rates, and steady-state occupations and we study their dependence on the tweezer ellipticity.

quant-ph↗

arXiv2021

Cooling nanorotors by elliptic coherent scattering

Simultaneously cooling the rotational and translational motion of nanoscale dielectrics into the quantum regime is an open task of great importance for sensing applications and quantum superposition tests. Here, we show that the six-dimensional ground state can be reached by coherent-scattering cooling with an elliptically polarized and shaped optical tweezer. We determine the cooling rates and steady-state occupations in a realistic setup and discuss applications for mechanical sensing and fundamental experiments.

quant-ph↗

arXiv2021

Orbital angular momentum interference of trapped matter waves

We introduce a matter wave interference scheme based on the quantization of orbital angular momentum in a ring trap. It operates without beam splitters, is sensitive to geometric phases induced by external gauge fields, and allows measuring interatomic scattering lengths. We argue that orbital angular momentum interferometry offers a versatile platform for quantum coherent experiments with cold atoms and Bose-Einstein condensates using state-of-the-art technology.

quant-ph↗

arXiv2021

Quantum rotations of nanoparticles

Rotations of microscale rigid bodies exhibit pronounced quantum phenomena that do not exist for their center-of-mass motion. By levitating nanoparticles in ultra-high vacuum, researchers are developing a promising platform for observing and exploiting these quantum effects in an unexplored mass and size regime. Recent experimental and theoretical breakthroughs demonstrate exquisite control of nanoscale rotations, setting the stage for the first table-top tests of rotational superpositions and for the next generation of ultra-precise torque sensors. Here, we review the experimental state of the art and discuss promising routes towards macroscopic quantum rotations.

quant-ph↗

arXiv2021

Enantiomer superpositions from matter-wave interference of chiral molecules

Molecular matter-wave interferometry enables novel strategies for manipulating the internal mechanical motion of complex molecules. Here, we show how chiral molecules can be prepared in a quantum superposition of two enantiomers by far-field matter-wave diffraction and how the resulting tunnelling dynamics can be observed. We determine the impact of ro-vibrational phase averaging and propose a setup for sensing enantiomer-dependent forces, parity-violating weak interactions, and environment-induced superselection of handedness, as suggested to resolve Hund's paradox. Using ab-initio tunnelling calculations, we identify [4]-helicene derivatives as promising candidates to implement the proposal with state-of-the-art techniques. This work opens the door for quantum sensing and metrology with chiral molecules.

quant-ph↗

arXiv2020

Quantum experiments with microscale particles

Quantum theory is incredibly successful, explaining the microscopic world with great accuracy, from the behaviour of subatomic particles to chemical reactions to solid-state electronics. There is not a single experimental finding challenging its predictions, and ever more quantum phenomena are exploited in technology, including interferometric sensing and quantum cryptography. In order to explore novel applications and test the validity of quantum physics at the macroscale researchers strive to prepare ever heavier and bigger objects in quantum superpositions. Experiments with levitated microscale particles are about to push this quest into uncharted waters.

quant-ph↗

arXiv2020

Bragg diffraction of large organic molecules

We demonstrate Bragg diffraction of the antibiotic ciprofloxacin and the dye molecule phthalocyanine at a thick optical grating. The observed patterns show a single dominant diffraction order with the expected dependence on the incidence angle as well as oscillating population transfer between the undiffracted and diffracted beams. We achieve an equal-amplitude splitting of $14 \hbar k$ (photon momenta) and maximum momentum transfer of $18 \hbar k$. This paves the way for efficient, large-momentum beam splitters and mirrors for hot and complex molecules.

physics.optics↗