Interference in Quantum Mechanics

Jos Uffink, Jan Hilgevoord

Huai‐Yu Wang

In quantum mechanics, there are two interference mechanisms between identical particles. One is that the de Broglie wavelengths of two interference waves are the same, which is called the equal wavelength interference mechanism. There have been many experiments by this mechanism. The other is that the wavelengths of interference waves can also be different, in which case there should be an exchange term in addition to the direct term in the wave function. There is a fixed phase difference between the two terms, which causes interference. This is called exchange effect interference mechanism. There is a special case where two interference waves can satisfy both the two mechanisms. We propose an experiment to discriminate that in this case which mechanism plays a role on earth. By the exchange effect interference mechanism, it is possible to construct artificial crystals and to study the physical properties of this kind of crystals.

Yoon-Ho Kim, Maria V. Chekhova, S. P. Kulik +1 more

Summary form only given. The superposition principle is at the heart of quantum mechanics and plays the central role in interference phenomena in quantum mechanics. Quantum interference differs from classical interference because of particle nature of light. In a quantum mechanical picture, interference occurs because there are indistinguishable ways of an event to occur. Whenever which-path information is given to the system, interference disappears. We have experimentally demonstrated that two-photon interference occurs for biphoton amplitudes arising from two well-separated pump pulses.

Chris Philippidis, Christopher Dewdney, Basil J. Hiley

A. Shalom, J. Žák

Urbasi Sinha, Christophe Couteau, Thomas D. Jennewein +2 more

Quantum mechanics and gravitation are two pillars of modern physics. Despite their success in describing the physical world around us, they seem to be incompatible theories. There are suggestions that one of these theories must be generalized to achieve unification. For example, Born's rule--one of the axioms of quantum mechanics--could be violated. Born's rule predicts that quantum interference, as shown by a double-slit diffraction experiment, occurs from pairs of paths. A generalized version of quantum mechanics might allow multipath (i.e., higher-order) interference, thus leading to a deviation from the theory. We performed a three-slit experiment with photons and bounded the magnitude of three-path interference to less than 10(-2) of the expected two-path interference, thus ruling out third- and higher-order interference and providing a bound on the accuracy of Born's rule. Our experiment is consistent with the postulate both in semiclassical and quantum regimes.