Temporally separated entanglement

consciousnessEntanglement between photons that have never coexisted

Megidish, E. H. S. Eisenberg et al, University of Jerusalem

arXiv:1209.4191v1 [quant ph] 19 Sep 2012

This study demonstrates that entanglement is not only between spatially separated quanta, but also between temporally separated quanta, or in other words it is extended across spacetime. This study utilises an experimental procedure from the 1990s known as entanglement swapping. The experiment involves two entangled pairs of photons, the first pair described as photon 1 and photon 2, and the second pair described as photon 3 and photon 4. There has been no previous interaction between the photons of the first pair and the photons of the second pair. However, it is possible in this experiment to subsequently entangle photons 2 and photons 3 (i.e. one photon from each of the initial pairs), and this will also result in photon 1 and photon 4 becoming entangled. The process is known as entanglement swapping, and it is utilised to deal with photon loss in long-range quantum communication.

Things had advanced that far by the late 1990s. However, in the 2012 experiment, photon 1 is detected and ‘dies’, before the entanglement of photon 2 and 3. Nevertheless, photons 1 and 4 still exhibit entanglement, inspite of never having coexisted in the same time frame. I quote here the rather daunting conclusion drawn by the study:

‘….. measuring the last photon affects the physical description of the first photon in the past, before it has even been measured. Thus the “spooky action” (refers to Einstein’s comment) is steering the system’s past. Another point of view is that the measurement of the first photon is immediately steering the future physical description of the last photon.’

This study does not engage with the implications of all this for consciousness. However, it seems feasible to relate it to two aspects of consciousness studies. Firstly, there is the suggestion that the conscious experience of the present moment is smeared out by perhaps as much as a few seconds over both the recollection of the immediate past and the expectations of the immediate future. This looks to have the advantage of avoiding having the present moment as a singularity, which might in turn imply a conflict with quantum theory.

Secondly, we have the Libet experiment that showed that up to 500ms of neural activity is required for a sensory input to come into consciousness, although the same experiments showed that subjects were unaware of the time lag. This led to the suggestion, unpopular with conventional thinking philosophers, that there could be backward referral in time within neural processing. However, this looks a bit less improbable if we remember that coherent and entangled states cover a range of probabilities. These do not have the irreversibility that comes with decoherence, and which relates to the increase of entropy, which is the hall mark of the passage of time.

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