Theory of microwave-optical conversion using rare-earth-ion dopants

Probing strong coupling between a microwave cavity and a spin ensemble with Raman heterodyne spectroscopy

“…Here we explore up-conversion processes in a crystal with isotopically purified 170 Er dopants at low temperatures (<1 K) using a single optical pass through the sample. Models suggest that with an optical resonator it is ultimately possible to achieve efficiencies of around 80% in this regime [36]. Our measurements are qualitatively compared with the predictions of these models, using Raman heterodyne spectroscopy with the spins being probed strongly coupled to a microwave resonator.…”

“…The individual ions are modeled using methods described in Refs. [30,36]. Because there is no cavity enhancement of the optical output field, this field will have a very small amplitude and we assume that this field does not drive the ions.…”

Quantum memory and manipulation based on erbium doped crystals

“…[Ú ‡Å […šþ!‚° Ä A:£Er:YSO 1AEá‚° •400 MHz § ‡Å‚° •5 MHz [25] ¤ § ÏL¦á óŠ3 áªÇNC §BOE±¼ š~OE š‚5 A"?˜Ú §ÏL¦^1AEnÚ ‡Å nÓžOr "¬NÚ ‡Å1f!OE"11fƒm ƒpŠ^ §BOE¢yþf Ç•100% $D(ªÇ = † [62] " ƒéuÙ¦ XÚ §ù˜•Y `:Äk3u( {ü §N´ì ‡z ¶, § †1Å XÚ¥ [66] ¶' ¦‚ÏL?˜Úr1AEnÚ\ XÚ¥ §ò= † ÇJp 10 −5 Y² [67] "3¦‚ ¢ ¥ §•›Ù = † Ç Ì ‡Ïƒ´Ù4 K óŠ §Ý §3ù˜ §Ýe §5 GHz ‡Å&ÒéA"lf ü ‡ [U?ƒ m >fÙÛêA ´ƒ "XJOE±?˜Úü mK §Ý±e §@o¤k >fѬ e% g^Ä §á š‚5òOEOEOr" OŽL² §3100 mK §Ýe §Ù= † ÇOE± † Jp 80% [68] " , §3mK §Ýe ¢ ò¡ ˜X Eâþ (J [69]…”

Nanocavity-Mediated Purcell Enhancement of Er in TiO2 Thin Films Grown via Atomic Layer Deposition

“…Future quantum networks may bring tremendous improvement to realms of secure communication, distributed quantum computing, and remote quantum sensing . In order for quantum networks to achieve reliable information transfer over long distances with suitable bandwidth, the network nodes must eventually employ quantum repeaters to overcome lossy single photon channels. − Trivalent erbium (Er 3+ or Er for brevity) is a workhorse emitter used in traditional telecommunications technology, and Er ions have recently emerged as promising communication qubits due to their narrow telecom C-band optical transition , and long electron spin coherence times. − Individual Er ions have already shown promise as a quantum memory element in repeaters, demonstrating storage via the spin state for use in future entanglement swapping protocols. − In addition, photonics-integrated ensembles of Er ions have also been applied in microwave-to-optical quantum state transduction, − to address the challenge of interfacing the optical photons used in quantum networks (∼195 THz) with processing nodes operating at microwave frequencies (∼10 GHz). However, despite these benefits, the long-lived optical lifetime of the telecom C-band transition has limited its development as nanophotonic cavities are necessary to enhance light–matter interactions and greatly decrease the photon excited state lifetime via Purcell enhancement.…”

“… 8 − 10 Individual Er ions have already shown promise as a quantum memory element in repeaters, demonstrating storage via the spin state for use in future entanglement swapping protocols. 11 − 13 In addition, photonics-integrated ensembles of Er ions have also been applied in microwave-to-optical quantum state transduction, 14 − 16 to address the challenge of interfacing the optical photons used in quantum networks (∼195 THz) with processing nodes operating at microwave frequencies (∼10 GHz). However, despite these benefits, the long-lived optical lifetime of the telecom C-band transition has limited its development as nanophotonic cavities are necessary to enhance light–matter interactions and greatly decrease the photon excited state lifetime via Purcell enhancement.…”