Gigahertz measurement-device-independent quantum key distribution using directly modulated lasers

NPJ QUANTUM INFORMATION 7:1 (2021) ARTN 58

Authors:

RI Woodward, YS Lo, M Pittaluga, M Minder, TK Paraiso, M Lucamarini, ZL Yuan, AJ Shields

An optically heated atomic source for compact ion trap vacuum systems.

The Review of scientific instruments 92:3 (2021) 033205

Authors:

S Gao, WJ Hughes, DM Lucas, TG Ballance, JF Goodwin

Abstract:

We present a design for an atomic oven suitable for loading ion traps, which is operated via optical heating with a continuous-wave multimode diode laser. The absence of the low-resistance electrical connections necessary for Joule heating allows the oven to be extremely well thermally isolated from the rest of the vacuum system. Extrapolating from high-flux measurements of an oven filled with calcium, we calculate that a target region number density of 100 cm-3, suitable for rapid ion loading, will be produced with 175(10) mW of heating laser power, limited by radiative losses. With simple feedforward to the laser power, the turn-on time for the oven is 15 s. Our measurements indicate that an oven volume 1000 times smaller could still hold enough source metal for decades of continuous operation.

Coherent manipulation of the internal state of ultracold 87Rb133Cs molecules with multiple microwave fields.

Physical chemistry chemical physics : PCCP 22:47 (2020) 27529-27538

Authors:

Jacob A Blackmore, Philip D Gregory, Sarah L Bromley, Simon L Cornish

Abstract:

We explore coherent multi-photon processes in 87Rb133Cs molecules using 3-level lambda and ladder configurations of rotational and hyperfine states, and discuss their relevance to future applications in quantum computation and quantum simulation. In the lambda configuration, we demonstrate the driving of population between two hyperfine levels of the rotational ground state via a two-photon Raman transition. Such pairs of states may be used in the future as a quantum memory, and we measure a Ramsey coherence time for a superposition of these states of 58(9) ms. In the ladder configuration, we show that we can generate and coherently populate microwave dressed states via the observation of an Autler-Townes doublet. We demonstrate that we can control the strength of this dressing by varying the intensity of the microwave coupling field. Finally, we perform spectroscopy of the rotational states of 87Rb133Cs up to N = 6, highlighting the potential of ultracold molecules for quantum simulation in synthetic dimensions. By fitting the measured transition frequencies we determine a new value of the centrifugal distortion coefficient Dv = h × 207.3(2) Hz.

Controlling the ac Stark effect of RbCs with dc electric and magnetic fields

PHYSICAL REVIEW A 102:5 (2020) ARTN 053316

Authors:

Jacob A Blackmore, Rahul Sawant, Philip D Gregory, Sarah L Bromley, Jesus Aldegunde, Jeremy M Hutson, Simon L Cornish

Loss of Ultracold ^{87}Rb^{133}Cs Molecules via Optical Excitation of Long-Lived Two-Body Collision Complexes.

Physical review letters 124:16 (2020) 163402

Authors:

Philip D Gregory, Jacob A Blackmore, Sarah L Bromley, Simon L Cornish

Abstract:

We show that the lifetime of ultracold ground-state ^{87}Rb^{133}Cs molecules in an optical trap is limited by fast optical excitation of long-lived two-body collision complexes. We partially suppress this loss mechanism by applying square-wave modulation to the trap intensity, such that the molecules spend 75% of each modulation cycle in the dark. By varying the modulation frequency, we show that the lifetime of the collision complex is 0.53±0.06  ms in the dark. We find that the rate of optical excitation of the collision complex is 3_{-2}^{+4}×10^{3}  W^{-1} cm^{2} s^{-1} for λ=1550  nm, leading to a lifetime of <100  ns for typical trap intensities. These results explain the two-body loss observed in experiments on nonreactive bialkali molecules.