Photon Intensity Interferometry Research Articles

Entanglement Enabled Intensity Interferometry of different wavelengths of light

We propose methods to perform intensity interferometry of photons having two different wavelengths. Distinguishable particles typically cannot interfere with each other, but we overcome that obstacle by processing the particles via entanglement and projection so that they lead to the same final state at the detection apparatus. Specifically, we discuss how quasi-phase-matched nonlinear crystals can be used to convert a quantum superposition of light of different wavelengths onto a common wavelength, while preserving the phase information essential for their meaningful interference. We thereby gain access to a host of new observables, which can probe subtle frequency correlations and entanglement. Further, we generalize the van Cittert–Zernike formula for the intensity interferometry of extended sources, demonstrate how our proposal supports enhanced resolution of sources with different spectral character, and suggest potential applications.

Single Photon Emission from a Plasmonic Light Source Driven by a Local Field-Induced Coulomb Blockade.

A hallmark of quantum control is the ability to manipulate quantum emission at the nanoscale. Through scanning tunneling microscopy-induced luminescence (STML), we are able to generate plasmonic light originating from inelastic tunneling processes that occur in the vacuum between a tip and a few-nanometer-thick molecular film of C60 deposited on Ag(111). Single photon emission, not of molecular excitonic origin, occurs with a 1/e recovery time of a tenth of a nanosecond or less, as shown through Hanbury Brown and Twiss photon intensity interferometry. Tight-binding calculations of the electronic structure for the combined tip and Ag–C60 system results in good agreement with experiment. The tunneling happens through electric-field-induced split-off states below the C60 LUMO band, which leads to a Coulomb blockade effect and single photon emission. The use of split-off states is shown to be a general technique that has special relevance for narrowband materials with a large bandgap.

Quantum Simulators and Quantum Repeaters

Two elements of quantum computation are considered: quantum computer logic and quantum repeater. It is shown that the quantum gate logic does have two different models and that it is therefore ambiguous. It is also shown that without additional conditions imposed on quantum gates one cannot arrive at a general quantum computer machine language. In absence of such conditions quantum entanglement remains a selection protocol which makes quantum computer equivalent to many photon intensity interferometry. As an example for such an entanglement we discuss a quantum optical repeater.

Photon intensity interferometry for expanding sources

Using Quantum Field Theory we derive a general formula for the double inclusive spectra of photons radiated by a system in local equilibrium. The derived expression differs significantly from the one mostly used up to now in photon intensity interferometry of heavy-ion collisions. We present a covariant expression for double inclusive spectra adapted for usage in numerical simulations. Application to a schematic model with a Bjørken-type expansion gives strong evidence for the need of reinvestigating photonphoton correlations for expanding sources.

Photon intensity interferometry with multidetectors

The technique of two-photon interferometry in heavy ion collisions at the intermediate energies is discussed and the importance of a new methodology, used in the treatment of the experimental data, is evidenced. For the first time, both the relative momentum, qrel, and the relative energy, q0, of the two correlated photons have been simultaneously used to extract the source size and lifetime of the emitting source. As an application, the performances of the BaF2 ball of the MEDEA multidetector as a photon intensity interferometer have been evaluated. The response of such a detector to correlated pairs of photons has been studied through full GEANT3 simulations. The effects of the experimental filter on the photon correlation function have been investigated, and the noise, induced in the correlation signal by cosmic radiation, neutral pion decay, and γ-conversion, has also been estimated.

Hard photon intensity interferometry in heavy ion reactions.

Intensity correlations between hard photons produced in heavy ion collisions have been measured for ${\mathit{E}}_{\ensuremath{\gamma}}$\ensuremath{\ge}25 MeV in the reaction $^{86}\mathrm{Kr}$${+}^{\mathrm{nat}}$Ni at 60A Mev bombarding energy. The observed correlation pattern is interpreted in terms of intensity interference. A correlation length of ${\mathit{C}}_{\mathrm{\ensuremath{\sigma}}}$=16\ifmmode\pm\else\textpm\fi{}4 MeV is found and the deduced photon source extent is discussed.

Dynamical properties of heavy-ion collisions from photon intensity interferometry

We consider the bremsstrahlung emission of photons at low and intermediate energies E lab⩽200 MeV/u of the projectile and derive expressions more general than previous results obtained by Neuhauser which were limited to the case of isotropic systems. We find that the two-photon correlation function strongly depends not only on the spacetime properties of the collision region but also on the dynamics of the proton-neutron scattering process in nuclear matter. As a consequences of polarisation correlations it turns out that for a purely chaotic source the intercept of the correlation function of photons can reach the value 3 (as compared with the maximum value 2 for isotropic systems). Furthermore even for “hard” photons (E γ > 25 MeV) the maximum of the correlation function can reach the value of 2 in contrast with the value of 1.5 derived by Neuhauser for this case.