N. S. Babcock, G. Montes-Cabrera, K. E. Oberhofer, M. Chergui, G. L. Celardo and P. Kurian (2024), The Journal of Physical Chemistry B 128(17):4035–4046 — DOI-10.1021/acs.jpcb.3c07936; preprint ARXIV-2302.01469
Key takeaways
- Prediction. Treat each tryptophan in a protein architecture as a two-level emitter (1La transition, 280 nm, 6 D, single-molecule radiative lifetime about 1.9 ns) coupled to the others through the electromagnetic field. Then the hierarchy tubulin dimer → microtubule → centriole or axon-like bundle has collective eigenmodes whose decay rates range from far above to far below a single tryptophan’s. The brightest centriole state saturates near 4000 γ once the structure is a few wavelengths long; axon-like bundles extrapolate toward about 7000 γ. The brightest states live 0.4–4 ps and the darkest up to about 14 s in arXiv v1’s Table S3; the published abstract says “hundreds of femtoseconds” and “tens of seconds”.
- Robustness is a property of the quantum yield, not of the superradiance. Static disorder of 200 cm⁻¹ cuts the centriole’s peak enhancement from about 3600 to about 20 (Fig. 5), yet the thermally averaged quantum yield is almost unchanged (Fig. 4). The reason given is that the dipole strength stays within k_BT of the lowest exciton band. The enhancement also needs larger disorder to degrade as the structure grows, which the authors call cooperative robustness.
- Measurement. The tryptophan-weighted fluorescence quantum yield falls from free tryptophan (12.4 ± 1.1%) to the tubulin dimer (10.6 ± 0.6%) and rises in microtubules to 17.6 ± 2.1%, the mean of a scattering-corrected upper bound and an uncorrected lower bound. At 295 nm excitation the values are 11.4, 10.9 and 14.7% (Table 1). This is “in qualitative agreement” with the model. The authors themselves say it must be complemented by lifetime measurements, which were not made.
Standing in the record
Filed on 2026-10-03 at the owner’s request, with Derakhshani et al. (LIT-627), as one of two pieces of evidence bearing on Penrose and Hameroff’s Orch OR theory of consciousness: one physical and measured, one experimental and a bound. No anthology topic holds quantum optics of proteins, and the paper carries no instruction for machine-learning practice.
What it bears on, precisely. The paper never mentions consciousness, Orch OR, Penrose or Hameroff. Its only link to that programme is a citation (ref. 54) to Kalra et al. on UV light-harvesting in microtubules, of which Hameroff and Penrose are co-authors. Read against Orch OR, it answers one generic objection for one kind of state: collective, coherent electronic excitation of an ordered chromophore lattice is predicted to survive room-temperature static disorder, and its expected signature, a rise in quantum yield with network size, is seen between tubulin dimers and microtubules in vitro. It does not touch what Orch OR adds to that:
- The states here are single electronic excitations shared across chromophores; the bright ones decay in picoseconds. Orch OR’s “OR” is, in McQueen’s summary of the theory’s core (quoted in LIT-627), a real, gravity-related wavefunction collapse, and its “Orch” is the claim that consciousness depends on orchestrated collapses in microtubules. No collapse model appears in this paper, and nothing in it concerns gravity.
- Nothing is measured in neurons or in tissue. The bundles and centrioles are simulated; the spectroscopy is on purchased, taxol-stabilised porcine-brain microtubules in buffer. The neural speculation (axons as waveguides between superradiant emitters, “ultrafast information transfer” from metabolic photons) is in the Discussion and Conclusions, unsupported by any result in the paper.
- Dynamic disorder (exciton–phonon coupling) is not modelled, as the authors say.
So it is evidence that collective quantum optical states can exist in microtubule-scale protein lattices at room temperature. It is not evidence for the claim that consciousness depends on them, and it is silent on the collapse half of the theory. That half is what Derakhshani et al. (LIT-627) test against underground radiation data.
The record’s other mentions of the programme are Chalmers’s dismissal of quantum theories as explaining “more functions at best” (LIT-406, read in NOTE-336) and Gao’s critique of Penrose’s gravity-collapse argument (LIT-121, NOTE-140). Neither bears on this paper’s physics: Chalmers’s point is about what any mechanism could explain, and Gao’s is about collapse, which this paper does not use.
Tagged natural-sciences first (molecular photophysics and protein
biophysics) and complex-systems for its central result, a collective
optical response and a robustness that grows with system size. It is not
tagged consciousness or neuroscience, because it is not about either; its
bearing on Orch OR is the record’s question, not the paper’s subject. The
vocabulary has no word for quantum biology. natural-sciences holds it for
now.
No relation is declared. The record holds none of the works it builds on (Celardo et al. 2019 on superradiance in single microtubules, ref. 28), and nothing it compares itself against.