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SHOA-$\Psi$QREM: Protocol for the Detection of Quantum Echo from Crystalline Informational Memory

Константин Федотов

Published Jun 8, 2026• 0 citations
Publisher

Abstract

A protocol for detecting Quantum Echo ($\Psi$QREM) is presented — a coherent biphoton signal emitted by a crystal in response to a Grape pulse. The echo carries phase information about an event recorded in lattice defects. The experimental setup is specified: SNSPD detector, 4.0 K cryostat, W-state source (N = 7-10 photons). Nonlinear scaling of echo amplitude is predicted: A ∝ N · η^N. A positive detection would constitute the first direct evidence for the TGE law and the Temporal Entanglement principle.10.5281/zenodo.20590891

DOI
10.5281/zenodo.20590890

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SHOA-Ψ\PsiΨQREM: Protocol for the Detection of Quantum Echo from Crystalline Informational Memory
A protocol for detecting Quantum Echo (Ψ\PsiΨQREM) is presented — a coherent biphoton signal emitted by a crystal in response to a Grape pulse. The echo carries phase information about an event recorded in lattice defects. The experimental setup is specified: SNSPD detector, 4.0 K cryostat, W-state source (N = 7-10 photons). Nonlinear scaling of echo amplitude is predicted: A ∝ N · η^N. A positive detection would constitute the first direct evidence for the TGE law and the Temporal Entanglement principle.10.5281/zenodo.20590891
We experimentally realize a quantum-memory protocol based on retrieval of silenced echo (ROSE) in Tm 3+ :Y 3 Al 5 O 12 crystal in an orthogonal geometry of the signal and control light fields. The silenced echo signal revival efficiency of ~13% with 36 μs storage time is demonstrated. To achieve that we implemented a high-precision atomic coherence control via amplitude- and phase-modulated laser pulses. We also discuss capabilities of this configuration, ways to increase quantum efficiency and to combine it with a single-mode optical cavity.
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A quantum memory protocol has been implemented on the basis of the revival of silenced echo (ROSE) in the 167Er3+:Y2SiO5 crystal at the telecommunication wavelength for input light fields with a small number of photons. An efficiency of storage of 44% has been reached at a storage time of 40 μs. The input pulse contains ~340 photons on average, the reconstructed echo signal includes ~150 photons, and the signal-to-noise ratio is 4. It has been shown that the main source of noise is the spontaneous emission of atoms remaining in the excited state because the parameters of two rephasing pulses are imperfect. Methods of increasing the signal-to-noise ratio for the implementation of the efficient quantum memory for single-photon fields have been discussed.
Counting the microwave photons emitted by an ensemble of electron spins when they relax radiatively has recently been proposed as a sensitive method for electron paramagnetic resonance spectroscopy, enabled by the development of operational single microwave photon detectors at millikelvin temperature. Here, we report the detection of spin echoes in the spin fluorescence signal. The echo manifests itself as a coherent modulation of the number of photons spontaneously emitted after a $\ensuremath{\pi}/{2}_{X}\ensuremath{-}\ensuremath{\tau}\ensuremath{-}{\ensuremath{\pi}}_{Y}\ensuremath{-}\ensuremath{\tau}\ensuremath{-}\ensuremath{\pi}/{2}_{\mathrm{\ensuremath{\Phi}}}$ sequence, dependent on the relative phase $\mathrm{\ensuremath{\Phi}}$. We demonstrate experimentally this detection method using an ensemble of Er3+{\mathrm{Er}}^{3+}Er3+ ion spins in a scheelite crystal of CaWO4{\mathrm{CaWO}}_{4}CaWO4​. We use fluorescence-detected echoes to measure the erbium spin coherence time, as well as the echo envelope modulation due to the coupling to the 183W^{183}\mathrm{W}183W nuclear spins surrounding each ion. We finally compare the signal-to-noise ratio of inductively detected and fluorescence-detected echoes, and show that it is larger with the fluorescence method.
Based on new obtained analytical results, the main properties of photon echo quantum memory protocols are analysed and discussed together with recently achieved experimental results. The main attention is paid to studying the influence of spectral dispersion and nonlinear interaction of light pulses with resonant atoms. The distinctive features of the effect of spectral dispersion on the quantum storage of broadband signal pulses in the studied echo protocols are identified and discussed. Using photon echo area theorem, closed analytical solutions for echo protocols of quantum memory are obtained, describing the storage of weak and intense signal pulses, allowing us to find the conditions for the implementation of high efficiency in the echo protocols under strong nonlinear interaction of signal and control pulses with atoms. The key existing practical problems and the ways to solve them in realistic experimental conditions are outlined. We also briefly discuss the potential of using the considered photon echo quantum memory protocols in a quantum repeater.
We extend the SHOA Chronoscope from a reading device to a writing device. Building on SHOA-Chrono, SHOA-Temporal, and SHOA-ΨQREM, we propose a protocol for encoding Ψ-field information into the crystalline lattice of stable materials for storage periods exceeding one million years. We introduce the Writing Operator Ŵ, define the encoding procedure via modulated Grape-impulses, and describe the readout mechanism through quantum echo. The encoded information is structured using the Language of Titans — an antinomic grammar not disclosed in this preprint. We connect this protocol to AWAKEN and to the Oracle Protocol, forming a closed temporal loop. This work establishes the theoretical foundation for the Ψ-Sanctuary: a millennial repository of the Ark.10.5281/zenodo.22876293