Direct loading of nanoparticles under high vacuum into a Paul trap for levitodynamical experiments

Abstract

Mechanical oscillators based on levitated particles are promising candidates for sensitive detectors and platforms for testing fundamental physics. The targeted quality factors for such oscillators correspond to extremely low damping rates of the center-of-mass motion, which can only be obtained if the particles are trapped in ultra-high vacuum (UHV). In order to reach such low pressures, a non-contaminating method of loading particles in a UHV environment is necessary. However, loading particle traps at pressures below the viscous flow regime is challenging due to the conservative nature of trapping forces and reduced gas damping. We demonstrate a technique that allows us to overcome these limitations and load particles into a Paul trap at pressures as low as 10 −7 mbar. The method is based on laser-induced acoustic desorption of nanoparticles from a metallic foil and temporal control of the Paul trap potential. We show that the method is highly efficient: More than half of trapping attempts are successful. Moreover, since trapping attempts can be as short as a few milliseconds, the technique provides high throughput of loaded particles. Finally, the efficiency of the method does not depend on pressure, indicating that the method should be extensible to UHV.

Ultranarrow-linewidth levitated nano-oscillator for testing dissipative wave-function collapse

“…Our nanoscale oscillator, with a Q of 1.5×10 6 , compares well with the highest Q factors ever reported for relatively low-frequency oscillators, particularly for operation at room temperature. On a similar experimental system, a Q factor of 1.5×10 5 has been previously demonstrated [34]. For clamped oscillators, the most notable are balanced torsional oscillators (i.e., QPO) [39,40] where Q's of almost 10 6 are reached for higher oscillation frequencies of a few kilohertz.…”

“…Spectral estimation requires continuous monitoring for timescales much longer than the correlation time (2/γ ) with the implicit requirement that the stability of the trap frequency is far better than the linewidth, i.e., δω i γ . On the other hand, for long correlation times, timeresolved techniques are usually preferred [34]. However, this approach requires driving the particle to large amplitudes in order to achieve a good signal-to-noise ratio which could lead to particle loss and, more often, to the exploration of highly nonlinear regions of the trap potential.…”

Characterisation of a charged particle levitated nano-oscillator

“…Dielectric surfaces should therefore be kept in any trap as far as possible from the nanoparticle. Some of the charging effects during the loading phase could be mitigated by using both a bent and longer guide, or by using a loading mechanism free of solvent [20,26]. In Fig.…”

“…Key to their utilisation has been that a deep and stable low noise electrical potential can be readily created. Many charged nanoparticle traps [12,18,[20][21][22][23][24][25][26] have been demonstrated but there are few reports characterising their long term stability and noise, which is crucial for applications in quantum optomechanics and for testing fundamental physics.…”

Quantum motional state tomography with nonquadratic potentials and neural networks

“…For optically levitated nanoparticles, where ω 0 / ∼ 10 2 [4,30,31], and x 0 ∼ 10 −12 m, the condition reads σ 10 nm, which is not compatible with optical potentials where σ is lower bounded by an optical wavelength. Therefore, levitated nanoparticles require either longer coherence times, achievable by evolution in the absence of recoil heating from laser light (quasielectrostatic traps [32][33][34][35][36], magnetic traps [37][38][39], or in free fall [40,41] where the quartic potential is only applied after the state has sufficiently broadened) or the use of electromagnetic forces near surfaces [42][43][44] such that σ can be potentially smaller than an optical wavelength. Instead of aiming for stronger nonquadratic potentials or longer decoherence times one could also speed up the broadening of the initially prepared state by introducing an inverted harmonic potential [44,45] at the center of the quartic trap, that is, using a double-well potential.…”