Phonon-limited detection thresholds for genetically encoded fluorescent-protein spin-qubit relaxometry of neural radicals

• URL: http://arxiv.org/abs/2609.02792v1
• Date: Wed, 02 Sep 2026 16:25:19 GMT
• Title: Phonon-limited detection thresholds for genetically encoded fluorescent-protein spin-qubit relaxometry of neural radicals
• Abstract summary: Enhanced yellow fluorescent protein hosts an optically addressable spin-1 qubit in its metastable triplet state.<n>We develop a detection-limit theory for using this fluorescent-protein spin qubit to sense paramagnetic neural signaling radicals by spin relaxometry.
• Score: 0.26097841018267615
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The demonstration that enhanced yellow fluorescent protein hosts an optically addressable spin-1 qubit in its metastable triplet state raises the prospect of genetically encoded quantum sensing at molecular length scales. We develop a detection-limit theory for using this fluorescent-protein spin qubit (FPSQ) to sense paramagnetic neural signaling radicals by spin relaxometry. We derive the transition-resolved Redfield relaxation matrix of the zero-field-split triplet coupled to a diffusing radical bath, establish the regime in which it collapses to a single exponential, and validate it against Lindblad simulations and nitrogen-vacancy benchmarks. Propagating the effects of photon shot noise, photobleaching-grounded photon budget, and finite measurement bandwidth, we find that the native room-temperature sensor falls short of physiological sensitivity by six to eight orders of magnitude with the bottleneck being the phonon-limited intrinsic $\Tone$. Analyzing the underlying direct and two-phonon Raman processes, we show that room-temperature relaxation is Raman-dominated by $\sim\!720\!:\!1$ and that, because the Raman coefficient scales as $v^{-10}$ with sound velocity, a $\sim\!2\times$ stiffening of the chromophore environment recovers $\Tone\sim\SI{100}{\micro\second}$, sufficient for micromolar sensing. Nanomolar sensing is obstructed by a direct-process ceiling of \SI{79}{\micro\second} that vibronic decoupling alone cannot breach. We obtain quantitative design rules, identify photon yield as a co-equal bottleneck, and propose a frequency-resolved protocol for chemical specificity.

Related papers

• Sensitivity Scaling and Limits of Cavity Enhancement in Miniaturized Optically Pumped Magnetometers [0.0]
  We model the photon-shot-noise-limited sensitivity of cavity-enhanced OPMs in the regime of strongly collisionally broadened optical transitions.<n>The cavity enhancement is benchmarked against a single-pass free-induction-decay OPM employing Faraday-rotation readout.<n>We show that, despite spin-dependent absorption associated with the ensemble's vector polarizability, near-critical coupling can be maintained throughout spin precession.
  arXiv  Detail & Related papers  (2026-08-17T14:59:09Z)
• Mapping photon-number regimes in single-emitter lasers [41.99844472131922]
  We present a numerical analysis of an open quantum system consisting of an incoherently pumped three-level emitter strongly coupled to a single cavity mode.<n>We find that laser behavior can emerge from minimal photon populations.<n>Our findings can be applied to define the operational limits of single-emitter light sources.
  arXiv  Detail & Related papers  (2026-06-30T07:10:49Z)
• Finite-Time Electrometry with a Quantum-Regime Single-Ion Phonon Laser [11.574116954665998]
  We report the first experimental realization of a quantum-regime single-ion phonon laser using a trapped $40mathrmCa+$ ion.<n>By tuning the phonon-laser parameters, we reveal that the sensing performance is governed by the finite-time relaxation dynamics of the underlying open quantum system.
  arXiv  Detail & Related papers  (2026-06-19T03:35:12Z)
• Ramsey correlation spectroscopy with phase cycling using a single quantum sensor [0.0]
  We present RESOLUTE, a protocol that overcomes limitations by combining Ramsey measurements with correlation spectroscopy.<n>We experimentally demonstrate an extension of the effective coherence time from $T* = 0.38,s$ to $Tp = 5.1,s$, surpassing Hahn Echo measurements.<n>These advancements provide enhanced sensitivity for single-molecule imaging and quantum sensing applications.
  arXiv  Detail & Related papers  (2026-03-05T19:59:24Z)
• Exponentially enhanced sensing through nonreciprocal light propagation [42.02177719060884]
  Non-reciprocal light propagation allows detecting small perturbations with a signal-to-noise ratio that scales exponentially with system size.<n>Our results open a new paradigm in non-Hermitian sensing, with potential applications in remote sensing including the optical readout of superconducting circuits.
  arXiv  Detail & Related papers  (2025-11-21T02:17:33Z)
• Annual-modulation fingerprint of the axion wind induced sideband triplet in quantum dot spin qubit sensors [0.0]
  We propose a phase-coherent, narrowband magnetometer for searching couplings between axions or axion-like particles (ALPs) and electron spins.<n>With repeated Ramsey echo sequences and dispersive readout, the qubit precession response can be tracked with sub-Hz spectral resolution.<n>Our results indicate that spin-qubit magnetometry can achieve sensitivities approaching those suggested by astrophysical considerations.
  arXiv  Detail & Related papers  (2025-11-05T16:49:24Z)
• Optimization and characterization of laser excitation for quantum sensing with single nitrogen-vacancy centres [36.136619420474766]
  We present a method of characterization and optimization of laser irradiation within a confocal microscope tailored to quantum sensing experiments.<n>We investigate the laser beam intensity profile, single-photon emission statistics, fluorescence response under varying polarization and saturation conditions, spectral characteristics, and the temporal profiles of readout and reinitialization pulses.
  arXiv  Detail & Related papers  (2025-07-14T15:27:22Z)
• A fluorescent-protein spin qubit [4.479457641989854]
  We realize an optically-addressable spin qubit in the Enhanced Yellow Fluorescent Protein (EYFP)<n>A near-infrared laser pulse allows for triggered readout of the triplet state with up to 44% spin contrast.<n>We express the qubit in mammalian cells, maintaining contrast and coherent control despite the complex intracellular environment.
  arXiv  Detail & Related papers  (2024-11-25T19:00:00Z)
• Measurement of small photon numbers in circuit QED resonators [42.01857709446569]
  Off-resonant interaction of fluctuating photons in a resonator with a qubit increases the qubit dephasing rate. We use this effect to measure a small average number of intracavity photons that are coherently or thermally driven.
  arXiv  Detail & Related papers  (2023-10-25T02:40:56Z)
• High-throughput quantum photonic devices emitting indistinguishable photons in the telecom C-band [28.279056210896716]
  Single indistinguishable photons at telecom C-band wavelengths are essential for quantum networks and the future quantum internet. We demonstrate the high- throughput fabrication of quantum-photonic integrated devices operating at C-band wavelengths based on epitaxial semiconductor quantum dots. Further improvements in yield and coherence properties will pave the way for implementing single-photon non-linear devices and advanced quantum networks at telecom wavelengths.
  arXiv  Detail & Related papers  (2023-04-05T15:39:22Z)
• Quantum density matrix theory for a laser without adiabatic elimination of the population inversion: transition to lasing in the class-B limit [62.997667081978825]
  No class-B quantum density-matrix model is available to date, capable of accurately describing coherence and photon correlations within a unified theory. Here we carry out a density-matrix theoretical approach for generic class-B lasers, and provide closed equations for the photonic and atomic reduced density matrix in the Fock basis of photons. This model enables the study of few-photon bifurcations and non-classical photon correlations in class-B laser devices, also leveraging quantum descriptions of coherently coupled nanolaser arrays.
  arXiv  Detail & Related papers  (2022-05-26T16:33:51Z)
• High speed microcircuit and synthetic biosignal widefield imaging using nitrogen vacancies in diamond [44.62475518267084]
  We show how to image signals from a microscopic lithographically patterned circuit at the micrometer scale. Using a new type of lock-in amplifier camera, we demonstrate sub-millisecond spatially resolved recovery of AC and pulsed electrical current signals. Finally, we demonstrate as a proof of principle the recovery of synthetic signals replicating the exact form of signals in a biological neural network.
  arXiv  Detail & Related papers  (2021-07-29T16:27:39Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.