Two-way interconversion of millimeter-wave and optical fields in Rydberg gases

Abstract

Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. / state. We find [46]Γ/ɣ = 1/285 and the ratio of the coupling constants is b = 0.72 . AbstractWe show that cold Rydberg gases enable an efficient six-wave mixing process where terahertz or microwave fields are coherently converted into optical fields and vice versa. This process is made possible by the long lifetime of Rydberg states, the strong coupling of millimeter waves to Rydberg transitions and by a quantum interference effect related to electromagnetically induced transparency. Our frequency conversion scheme applies to a broad spectrum of millimeter waves due to the abundance of transitions within the Rydberg manifold, and we discuss two possible implementations based on focussed terahertz beams and millimeter wave fields confined by a waveguide, respectively. We analyse a realistic example for the interconversion of terahertz and optical fields in rubidium atoms and find that the conversion efficiency can in principle exceed 90%.

Microwave-to-optical frequency conversion using a cesium atom coupled to a superconducting resonator

“…This indicates that two intervals is sufficient to obtain the majority of the performance. In contrast to previous works, which typically assume all Rabi frequencies are constant in time [30,31], we find that using time dependent pulses can greatly improve conversion efficiency. As a double-check and to employ a parametrization that is less discontinuous, we choose each envelope to be a Gaussian with a variable mean, amplitude, and width.…”

“…In these approaches the conversion is mediated by, respectively, a nano-mechanical resonator [7][8][9][23][24][25][26][27][28], an ensemble of trapped atoms [10,11,[29][30][31], and an ensemble of spins in a solid (e.g., NV-centers in diamond) [32][33][34][35][36]. A number of experiments have already demonstrated proof-ofprinciple conversion between microwaves and optical frequencies using a nano-mechanical system [25][26][27][28].…”

Microwave-to-optical conversion via four-wave mixing in a cold ytterbium ensemble

“…We must consider various inhomogeneous broadening mechanisms in the ensemble. Since we are interested in a single Rydberg excitation which is collectively enhanced by the N = 150 atoms, we can neglect Rydberg-Rydberg interactions such as van der Waals [53][54][55] and dipoledipole interactions [15]. Further, our ensemble is relatively dilute, with an average inter-atomic spacing of d ≈ 3.6 µm.…”

“…In the neutral atom approach, coupling to microwave photons is most notably mediated by transitions between two highly-excited Rydberg states since they have large transition electric dipole moments [13][14][15][16][17][18]. The desired microwave frequency can be selected simply by choosing the principle quantum number n of the Rydberg levels appropriately.…”

“…1). Specifically, we consider N = 150 174 Yb atoms with zero nuclear spin in a cigar-shaped geometry [15]. The ensemble is placed inside a copper microwave resonator with Q µ = 4.5 × 10 3 at resonance frequency f µ = 10.1 GHz.…”