We propose a novel experimental protocol that positions an isolated, naturally asymmetric Fenna–Matthews–Olson (FMO) light-harvesting complex from the green sulfur bacterium Chlorobaculum tepidum at one slit of a single-photon double-slit interferometer. The FMO trimer harbours two energetically inequivalent branches—one possessing an additional bridging bacteriochlorophyll at site 8—constituting a physically realised, biologically native which-path detector. We measure fringe visibility V = (I max − Imin) / (I max + Imin) as a function of FMO coupling strength, temperature (4–310 K), and genetic modification state, seeking to determine whether native biological asymmetry is sufficient to induce wavefunction collapse selectively at one slit. Three mutually exclusive hypotheses are tested: full collapse (H1), no collapse (H2), and continuous visibility reduction proportional to coupling strength (H3). We further propose a genetic tunability programme—spanning bchQ/bchR deletion mutants, site-directed mutagenesis at BChl-binding residues, and synthetic chromophore incorporation—that transforms the experiment from a binary yes/no test into a quantitative dose–response curve mapping the genotype-to-collapse continuum. A comprehensive literature survey confirms that this specific three-way intersection of double-slit interferometry, FMO asymmetry, and biological which-path detection has never been proposed or executed. The closest precedents—strong coupling of living C. tepidum to optical microcavities (Coles et al. 2017), quantum discord proposals for photosynthetic organisms (Krisnanda et al. 2018), and gold-nanoparticle observer experiments (2024)—each address only one vertex of this triangle. This proposal addresses all three simultaneously for the first time.
We propose a novel experimental protocol that positions an isolated, naturally asymmetric Fenna–Matthews–Olson (FMO) light-harvesting complex from the green sulfur bacterium Chlorobaculum tepidum at one slit of a single-photon double-slit interferometer. The FMO trimer harbours two energetically inequivalent branches—one possessing an additional bridging bacteriochlorophyll at site 8—constituting a physically realised, biologically native which-path detector. We measure fringe visibility V = (I max − Imin) / (I max + Imin) as a function of FMO coupling strength, temperature (4–310 K), and genetic modification state, seeking to determine whether native biological asymmetry is sufficient to induce wavefunction collapse selectively at one slit. Three mutually exclusive hypotheses are tested: full collapse (H1), no collapse (H2), and continuous visibility reduction proportional to coupling strength (H3). We further propose a genetic tunability programme—spanning bchQ/bchR deletion mutants, site-directed mutagenesis at BChl-binding residues, and synthetic chromophore incorporation—that transforms the experiment from a binary yes/no test into a quantitative dose–response curve mapping the genotype-to-collapse continuum. A comprehensive literature survey confirms that this specific three-way intersection of double-slit interferometry, FMO asymmetry, and biological which-path detection has never been proposed or executed. The closest precedents—strong coupling of living C. tepidum to optical microcavities (Coles et al. 2017), quantum discord proposals for photosynthetic organisms (Krisnanda et al. 2018), and gold-nanoparticle observer experiments (2024)—each address only one vertex of this triangle. This proposal addresses all three simultaneously for the first time.
Abstract Biological systems are currently analysed from deeper approaches considering not only their chemical features but also their quantum ones. Such elusive features sometimes account for specific phenomena related to their evolution and survival. Green sulphur bacteria are very simple microorganisms performing a highly photosynthetic process to survive. The Fenna-Mathew-Olson (FMO) complex is a macro-molecule responsible for such efficiency exhibiting interesting quantum features. Post-experimental biology together with Physics able the possibility to research and analyse them. In the current work, a synthetic roadmap for the FMO simulation is presented with comprehensive literature. The density matrix evolution is obtained to then discuss other derived features such as coherence, entanglement, state transference, and energy transmission efficiency.
The double-slit experiment has long been pivotal in understanding matter’s wave–particle duality. A central question revolves around Born’s interpretation of wavefunction whether a single photon demonstrates a 50% probability of passing through each slit individually as particles or simultaneously traverses both as waves. Experimentally, once the photon’s path is detected, the observer effect causes its wavefunction to collapse, rendering the results inconclusive. Designing an experiment to minimize instrumental involvement during the wavefunction collapse of photons, while aiming to gain insight into its collapse mechanism, becomes necessary. We propose a revised experiment that replaces the traditional setup with two Au nanoparticles acting as observers, triggering photon collapse before spectrum collection. In single-photon scenarios, we consider two assumptions: first, the photon wavefunctions collapse into a particle and transfer energy to one of the nanoparticles exclusively, and second, the photon acts as a wave, splitting and transferring its energy to two nanoparticles simultaneously, which does not align well with Born’s interpretation of wavefunction as spatial probabilities. These two assumptions would generate distinctly different spectra. Conversely, in high-intensity experiments, both nanoparticles collectively undergo excitation, regardless of the collapse mechanism. A comparative analysis of scattering spectra under the two conditions reveals crucial insights into the genuine nature of photon collapse. We also proposed using two molecules attached to a metal nanoparticle as an alternative design. Whether affirming or refuting the observer effect, this research holds promise for resolving the theoretical debate surrounding the collapse of wavefunctions and advancing quantum computing and communication fields.
Abstract Quantum effects in photosynthetic energy transport in nature, especially for the typical Fenna-Matthews-Olson (FMO) complexes, are extensively studied in quantum biology. Such energy transport processes can be investigated as open quantum systems that blend the quantum coherence and environmental noise, and have been experimentally simulated on a few quantum devices. However, the existing experiments always lack a solid quantum simulation for the FMO energy transport due to their constraints to map a variety of issues in actual FMO complexes that have rich biological meanings. Here we successfully map the full coupling profile of the seven-site FMO structure by comprehensive characterisation and precise control of the evanescent coupling of the three-dimensional waveguide array. By applying a stochastic dynamical modulation on each waveguide, we introduce the base site energy and the dephasing term in coloured noise to faithfully simulate the power spectral density of the FMO complexes. We show our photonic model well interprets the phenomena including reorganisation energy, vibrational assistance, exciton transfer and energy localisation. We further experimentally demonstrate the existence of an optimal transport efficiency at certain dephasing strength, providing a window to closely investigate environment-assisted quantum transport.
Fenna-Mathews-Olson complexes participate in the photosynthetic process of Sulfur Green Bacteria. These biological subsystems exhibit quantum features which possibly are responsible for their high efficiency; the latter may comprise multipartite entanglement and the apparent tunnelling of the initial quantum state. At first, to study these aspects, a multidisciplinary approach including experimental biology, spectroscopy, physics, and math modelling is required. Then, a global computer modelling analysis is achieved in the computational biology domain. The current work implements the Hierarchical Equations of Motion to numerically solve the open quantum system problem regarding this complex. The time-evolved states obtained with this method are then analysed under several measures of entanglement, some of them already proposed in the literature. However, for the first time, the maximum overlap with respect to the closest separable state is employed. This authentic multipartite entanglement measure provides information on the correlations, not only based on the system bipartitions as in the usual analysis. Our study has led us to note a different view of FMO multipartite entanglement as tiny contributions to the global entanglement suggested by other more basic measurements. Additionally, in another related trend, the initial state, considered as a Förster Resonance Energy Transfer, is tracked using a novel approach, considering how it could be followed under the fidelity measure on all possible permutations of the FMO subsystems through its dynamical evolution by observing the tunnelling in the most probable locations. Both analyses demanded significant computational work, making for a clear example of the complexity required in computational biology.
Abstract Fenna-Matthews-Olson (FMO) bacteriochlorophylls (BChls) are molecules responsible of the high efficiency energy transfer in the photosynthetic process of green sulfur bacteria, controversially associated to quantum phenomena of long lived coherence. This phenomenon is modelled using Quantum Open Systems (QOS) without include memory effects of the surrounding approximated as a phonon bath on thermal equilibrium. This work applies the Hierarchical Equations of Motion method (HEOM), a non-Markovian approach, in the modelling of the system evolution of FMO complex to perform predictions about the coherence times scales together with global and semi-local entanglement during the quantum excitation.
Standard double-slit and interferometer experiments treat apparatus geometry, boundary conditions, coherence, detector response, and which-path distinguishability as sufficient variables for predicting interference visibility. This paper preserves that standard quantum-optical null model as the baseline and asks a narrower residual question: whether a dynamically reconfigured two-path apparatus can show visibility dependence on the time at which the relevant apparatus context becomes locally available. The proposed apparatus-context hypothesis is intentionally carrier-neutral. It may be represented inside the broader space-cell program either by deformation-like geometry, stress, shear, or topology variables, or by an extrinsic scalar χ-like compression/event-density coordinate. The first experimental question is not which internal carrier is correct. It is whether any additional finite-speed apparatus-context variable is required after ordinary quantum-optical effects are modeled and controlled. The primary observable is residual visibility as a function of reconstructed apparatus-context delay, Δ_ctx = τ_interaction − τ_context available. Under this sign convention, Δ_ctx < 0 means the photon-apparatus interaction occurs before the relevant two-path context has become available, while Δ_ctx > 0 means the context is available before interaction. The proposed support signature is a reproducible negative residual in the negative-Δ_ctx timing window, absent in sham-switch, one-path, decoherence, detector-angle, path-phase, material, and deformation-only controls. The proposed experiment reflects findings from toy-model interaction/accounting tests and design-translation results. These simulations sharpen criteria for a falsifiable experiment, define controls, and translate the timing variable into implementable design constraints.