A detailed analysis of the most relevant sources of phase noise in an atomic interferometer is carried out, both theoretically and experimentally. Even a short interrogation time of 100 ms allows our ...cold atom gravimeter to reach an excellent short term sensitivity to acceleration of 1.4×10
-8
g at 1 s. This result relies on the combination of a low phase noise laser system, efficient detection scheme and good shielding from vibrations. In particular, we describe a simple and robust technique of vibration compensation, which is based on correcting the interferometer signal by using the ac acceleration signal measured by a low noise seismometer.
Friction in ordered atomistic layers plays a central role in various nanoscale systems ranging from nanomachines to biological systems. It governs transport properties, wear and dissipation. Defects ...and incommensurate lattice constants markedly change these properties. Recently, experimental systems have become accessible to probe the dynamics of nanofriction. Here, we present a model system consisting of laser-cooled ions in which nanofriction and transport processes in self-organized systems with back action can be studied with atomic resolution. We show that in a system with local defects resulting in incommensurate layers, there is a transition from sticking to sliding with Aubry-type signatures. We demonstrate spectroscopic measurements of the soft vibrational mode driving this transition and a measurement of the order parameter. We show numerically that both exhibit critical scaling near the transition point. Our studies demonstrate a simple, well-controlled system in which friction in self-organized structures can be studied from classical- to quantum-regimes.
Symmetry breaking phase transitions play an important role in nature. When a system traverses such a transition at a finite rate, its causally disconnected regions choose the new broken symmetry ...state independently. Where such local choices are incompatible, topological defects can form. The Kibble-Zurek mechanism predicts the defect densities to follow a power law that scales with the rate of the transition. Owing to its ubiquitous nature, this theory finds application in a wide field of systems ranging from cosmology to condensed matter. Here we present the successful creation of defects in ion Coulomb crystals by a controlled quench of the confining potential, and observe an enhanced power law scaling in accordance with numerical simulations and recent predictions. This simple system with well-defined critical exponents opens up ways to investigate the physics of non-equilibrium dynamics from the classical to the quantum regime.
We report on the first coherent excitation of the highly forbidden S21/2→F27/2 electric octupole (E3) transition in a single trapped Yb+172 ion, an isotope without nuclear spin. Using the transition ...in Yb+171 as a reference, we determine the transition frequency to be 642 116 784 950 887.6(2.4) Hz. We map out the magnetic field environment using the forbidden S21/2→D25/2 electric quadrupole (E2) transition and determine its frequency to be 729 476 867 027 206.8(4.4) Hz. Our results are a factor of 1×105 (3×105) more accurate for the E2 (E3) transition compared to previous measurements. The results open up the way to search for new physics via precise isotope shift measurements and improved tests of local Lorentz invariance using the metastable F27/2 state of Yb+.
Abstract
Trapped-ion quantum sensors have become highly sensitive tools for the search of physics beyond the Standard Model. Recently, stringent tests of local Lorentz-invariance (LLI) have been ...conducted with precision spectroscopy in trapped ions (Pruttivarasin
et al
2015
Nature
517
592–5, Megidish
et al
2019
Phys. Rev. Lett.
122
123605, Sanner
et al
2019
Nature
567
204–8, Dreissen
et al
2022
Nat. Commun.
13
1–6) . We here elaborate on robust radio-frequency composite-pulse spectroscopy at second long coherence times in the magnetic sublevels of the long-lived
2
F
7
/
2
state of a trapped
172
Yb
+
ion which is scalable to spatially extended multi-ion systems. We compare two Ramsey-type composite rf pulse sequences, a generalized spin-echo (GSE) sequence (Shaniv
et al
2018
Phys. Rev. Lett.
120
103202) and a sequence based on universal rotations with 10 rephasing pulses (UR10) (Genov
et al
2017
Phys. Rev. Lett.
118
133202) that decouple the energy levels from magnetic field noise, enabling robust and accurate spectroscopy. Both sequences are characterized theoretically and experimentally in the spin-
1
/
2
2
S
1
/
2
electronic ground state of
172
Yb
+
and results show that the UR10 sequence is 38 (13) times more robust against pulse duration (frequency detuning) errors than the GSE sequence. We extend our simulations to the eight-level manifold of the
2
F
7
/
2
state, which is highly sensitive to a possible violation of LLI, and show that the UR10 sequence can be used for high-fidelity Ramsey spectroscopy in noisy environments. The UR10 sequence is implemented experimentally in the
2
F
7
/
2
manifold and a coherent signal of up to 2.5 s is reached. In (Dreissen
et al
2022
Nat. Commun.
13
1–6) we have implemented this sequence and used it to perform the most stringent test of LLI in the electron–photon sector to date with a single Yb
+
ion. Due to the high robustness of the UR10 sequence, it can be applied on larger ion crystals to improve tests of Lorentz symmetry further. We demonstrate that the sequence can also be used to extract the quadrupole moment of the meta-stable
2
F
7
/
2
state, obtaining a value of
Θ
=
−
0.0298
(
38
)
e
a
0
2
which is in agreement with the value deduced from clock measurements (Lange
et al
2020
Phys. Rev. Lett.
125
143201).
Abstract
We report on a comparative analysis of quenched sideband cooling in trapped ions. We introduce a theoretical approach for time-efficient simulation of the temporal cooling characteristics ...and derive the optimal conditions providing fast laser cooling into the ion’s motional ground state. The simulations were experimentally benchmarked with a single
172
Yb
+
ion confined in a linear Paul trap. Sideband cooling was carried out on a narrow quadrupole transition, enhanced with an additional clear-out laser for controlling the effective linewidth of the cooling transition. Quench cooling was thus for the first time studied in the resolved sideband, intermediate and semi-classical regime. We discuss the non-thermal distribution of Fock states during laser cooling and reveal its impact on time dilation shifts in optical atomic clocks.
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