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Quantum logic gates using photon exchange interactions

T. B. Pittman, J. D. Franson

Summary form only given. Nonlinear interactions between two photons are normally very weak because of the weak electric field associated with a single photon. We recently suggested that this difficulty could be avoided by relying on exchange interactions, which can have large effects even when there is no physical interaction at all between two particles. We consider two photons in well collimated beams that are incident upon an atomic vapor cell. The probability of there being two excited atoms in the medium is shown to be a factor of two larger in that case than if the two photons were incident upon two separate but otherwise identical media.Summary form only given. Nonlinear interactions between two photons are normally very weak because of the weak electric field associated with a single photon. We recently suggested that this difficulty could be avoided by relying on exchange interactions, which can have large effects even when there is no physical interaction at all between two particles. We consider two photons in well collimated beams that are incident upon an atomic vapor cell. The probability of there being two excited atoms in the medium is shown to be a factor of two larger in that case than if the two photons were incident upon two separate but otherwise identical media.

Quantum Electronics and Laser Science ConferenceJan 20, 20030 citations

Quantum logic using photon-exchange interactions

Franson, Pittman

Quantum Electronics and Laser Science ConferenceJan 1, 20000 citations

One-photon controlled two-photon not gate contributed by weak cross-Kerr nonlinearities

Xiao‐Ming Xiu, Qing-Yang Li, Yan-Fang Lin +3 more

Optics CommunicationsFeb 23, 20176 citations

Quantum logic operations based on photon-exchange interactions

J. D. Franson, T. B. Pittman

Nonlinear interactions between two photons are required for the construction of optical quantum logic gates, but those interactions are normally very weak due to the small magnitude of the electric field associated with a single photon. We note that exchange interactions can have a large effect even when there is no physical interaction between two particles, and we exploit this property for the construction of optical quantum logic gates. We show that the probability of there being two virtually-excited atoms in a medium can be a factor of 2 larger when two nonresonant photons propagate through the same medium as compared to the case in which they propagate through two separate media, in analogy with photon bunching. As a result, the application of one or more laser pulses will produce a nonlinear phase shift that can be used to construct an XOR quantum logic gate. This provides an example of a quantum control process in which one photon can control the state of another photon even when there is no sequence of physical interactions linking the two photons. From a classical point of view, it is not possible to identify a path for the flow of information or a specific cause for the outcome of the control process.Nonlinear interactions between two photons are required for the construction of optical quantum logic gates, but those interactions are normally very weak due to the small magnitude of the electric field associated with a single photon. We note that exchange interactions can have a large effect even when there is no physical interaction between two particles, and we exploit this property for the construction of optical quantum logic gates. We show that the probability of there being two virtually-excited atoms in a medium can be a factor of 2 larger when two nonresonant photons propagate through the same medium as compared to the case in which they propagate through two separate media, in analogy with photon bunching. As a result, the application of one or more laser pulses will produce a nonlinear phase shift that can be used to construct an XOR quantum logic gate. This provides an example of a quantum control process in which one photon can control the state of another photon even when there is no sequence of physical interactions linking the two photons. From a classical point of view, it is not possible to identify a path for the flow of information or a specific cause for the outcome of the control process.

Physical Review AAug 1, 199927 citations

Quantum nonlinear optics with single photons enabled by strongly interacting atoms

Thibault Peyronel, Ofer Firstenberg, Qiyu Liang +5 more

NatureJul 24, 2012844 citations

Nonlinear optics at the two-photon level

J. D. Franson, T. B. Pittman

Summary form only given.Nonlinear optical effects are normally limited to high-intensity fields containing a large number of photons because the electric field associated with a single photon is usually very weak. Nonlinear phase shifts at the two-photon level previously have been observed using high-Q cavities and atomic beams. The authors recently predicted that nonlocal effects involving pairs of atoms in a medium could enhance the nonlinear interaction between two photons to the point that nonlinear phase shifts could be obtained in an ordinary medium without the use of resonant cavities.Summary form only given.Nonlinear optical effects are normally limited to high-intensity fields containing a large number of photons because the electric field associated with a single photon is usually very weak. Nonlinear phase shifts at the two-photon level previously have been observed using high-Q cavities and atomic beams. The authors recently predicted that nonlocal effects involving pairs of atoms in a medium could enhance the nonlinear interaction between two photons to the point that nonlinear phase shifts could be obtained in an ordinary medium without the use of resonant cavities.

Conference on Lasers and Electro-OpticsNov 27, 20020 citations

Quantum logic using photon-exchange interactions

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Quantum logic using photon-exchange interactions

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