Method and apparatus for selectively controlling the quantum...

Data processing: measuring – calibrating – or testing – Measurement system – Statistical measurement

Reexamination Certificate

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C359S199200

Reexamination Certificate

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06473719

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to quantum non-locality modulated signaling methods.
It has been demonstrated, by Aspect and others, that under some circumstances, certain atomic species and non-linear down conversion crystals can be induced to emit entangled pairs of photons that have correlated linear polarizations; the correlated linear polarizations of the photon pairs will be found to be either always mutually orthogonal, or mutually parallel, depending on the nature of the source, when observed in any linear polarization basis. The photons can be provided in separate streams, with either one of each pair in each stream or with each photon having an equal probability of being found in either stream. It has further been strongly demonstrated that, under certain conditions, these entangled photons are not emitted with any predetermined directions of linear polarization, but that the linear polarization states of both photons only become definite upon measurement of the linear polarization of one of the photons. Thus, assuming perpendicular polarization correlation, if one photon is measured to be vertically polarized, then the other photon becomes horizontally polarized at that moment, no matter how far apart the two photons have traveled prior to the measurement. The polarization states of the two photons are 100 percent entangled; measurement of the horizontal or vertical polarization state of one photon determines the vertical or horizontal polarization state, respectively of the other (where the linear polarization correlation of the entangled photons is perpendicular), but prior to measurement, their polarization states are indefinite. In essence, the two photons are parts of the same quantum object; regardless of how far the photons travel apart from each other, changing the properties of one photon instantly changes the properties of the whole object, including the properties of the other photon. The experiments of Aspect, et al., have convinced most quantum theorists that the polarizations of these entangled photons are non-local; the polarizations are not predetermined at the time of emission, but are rather condensed into a particular state at the moment of “observation” of one of them. A. Aspect, P. Grangier and G. Roger, Phys. Lett. 47, 460 (1981) and 49, 91 (1982). A. Aspect, J. Dalibard and G. Roger, Phys. Lett. 49, 1804 (1982); Z. Y. Ou and L. Mandel, Phys. Lett. 61, 50 (1988) and 61, 54 (1988).
The correlation of properties between space-like separated entangled quantum objects has been called the EPR effect, after the scientists Einstein, Podelsky, and Rosen, who first proposed that quantum mechanics predicted that the measurable properties of such entangled quantum objects could be non-local. Various recent experiments have demonstrated that the EPR effect occurs faster than the speed of light; the speed of the EPR effect is presumed to be instantaneous.
Various quantum theorists and experimentalists have addressed the question of whether the non-locality effects of entangled particles can be employed as the basis for sending information. The published conclusions of Aspect and others have asserted that such is not possible. Baggott, Jim,
The Meaning of Quantum Theory
, Oxford Science Publications, Oxford University Press, 1992, pp. 148-150; P. Eberhard and R. Ross, Found. Phys. Lett., 2, 127 (1989). Their logic is that the passage rate of either stream of entangled photons through its respective polarizer will always appear random. Although the correlation of polarization between the two photons is not random, the probability distribution of both the sender's and the receiver's photons will be uniformly distributed into the two observed polarization states, so the receiver cannot glean information from the photons he, alone, receives. The signal and the noise are, therefore, of equal magnitude.
These conclusions are correct, so far as they go. In the systems which have been previously analyzed, the entangled photon source, emitting photons in a ‘singlet’ state, the quantum state superposition of horizontal and vertical polarization with equal probability amplitudes, is placed midway between the sender and the receiver, two linear polarizers are employed, one at each end of the dual photon stream, one polarizer for the sender and one for the receiver, and the photon coincidence count rate for photons passing through the two polarizers is measured as a function of the angles of the polarizers. It does appear to be true that information cannot be sent by correlation of entangled photon polarizations by means of such an apparatus designed especially for coincidence counting. Indeed, coincidence counting itself implies the existence of a classical (non-quantum) channel over which to identify coincident detector events.
It appears that prior researchers in this field have assumed that information cannot be transmitted by polarization correlation using an apparatus consisting of an entangled photon source in the singlet state, two polarizers, and two or more detectors, and that it is therefore impossible to transmit information via quantum correlations between space-like separated photons in general. It has also been commonly assumed that once a photon passes through a linear polarizer its polarization state is fixed, and that passage of polarization-entangled photons through polarizing elements causes loss of polarization entanglement. Yet another key assumption by physicists is that the entanglement of a pair of quantum objects can only persist so long as the entangled pair exists in a superposition of joint quantum states.
The commonly held belief that information cannot be transmitted via quantum correlations between space-like separated entangled photons is based on the above assumptions. I have discovered that these assumptions are incorrect. In particular: a polarization-entangled photon pair does not become disentangled if one or both of the photons pass through a polarizer; existing in a superposition of joint quantum states is not a requirement for the persistence of entanglement in polarization entangled photons; and the polarization state of a photon is not immutably fixed by interaction with a polarizer. This correct understanding of the quantum physics of polarization-entangled photons, quantum entanglement, and photon polarization makes clear the utility of my invention.
By means of a quantum mechanical wave function analysis of a polarization-entangled photon experiment performed by T. Haji-Hassan, et. Al., I have discovered that the passage of one or more photons of an entangled photon pair through a polarizing element does not cause loss of polarization entanglement and that existing in a superposition of joint quantum states is not a requirement for the persistence of entanglement. Steenblik, Richard A.,
Experimental Proof that Passage Through a Polarizer Does Not Cause Loss of Entanglement
, Dec. 10, 1998, attached hereto as Appendix A. T. Haji-Hassan, A. Duncan, W. Perrie, and H. Kleinpoppen, “Polarization Correlation Analysis of the Radiation from a Two-Photon Deuterium Source Using Three Polarizers: A Test of Quantum Mechanics versus Local Realism”, Phys. Rev. Lett., 62, 237 (1989).
By means of the ‘Three-Polarizer Experiment’, described in the following pages, it is easily demonstrated that a definite polarization state of a photon in one polarization basis may be altered by subsequent polarization operations on that photon. The polarization state of a photon is therefore not ‘fixed’, or immutable, until it has actually been detected by absorption.
Based on these correct understandings of polarization-entangled photons, quantum entanglement, and photon polarization, I have discovered that additional polarizers, when properly arranged and controlled, allow the separation of signal information from noise in a singlet state entangled photon system and enable the use of such a system for the transmission of information. Furthermore, I have discovered that it is possible to employ quantum correlation effects to

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