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Quantum interference in electron collision


The indistinguishability of identical quantum particles can lead to quantum interferences that profoundly affect their scattering1,2. If two particles collide and scatter, the process that results in the detection of the first particle in one direction and the second particle in another direction interferes quantum mechanically with the physically indistinguishable process where the roles of the particles are reversed. For bosons such as photons, a constructive interference between probability amplitudes can enhance the probability, relative to classical expectations, that both are detected in the same direction — this is known as ‘bunching’. But for fermions such as electrons, a destructive interference should suppress this probability (‘anti-bunching’); this interference is the origin of the Pauli exclusion principle, which states that two electrons can never occupy the same state. Although two-particle interferences have been shown for colliding photons3,4, no similar demonstration for electrons exists2,5,6. Here we report the realization of this destructive quantum interference in the collision of electrons at a beam splitter. In our experiments, the quantum interference responsible for the Pauli exclusion principle is manifest as the suppression in electron current noise after collision.

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Figure 1: Scattering and collisions at a beam splitter.
Figure 2: Suppression of collision noise in an electron beam splitter.
Figure 3: Conductance and partition noise in a quantum point contact.


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We thank G. Austing and T. Honda for fabrication assistance, J. Kim for help with experiments and the Joint Services Electronics Program for graduate support to R.C.L.

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Correspondence to Y. Yamamoto.

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Liu, R., Odom, B., Yamamoto, Y. et al. Quantum interference in electron collision. Nature 391, 263–265 (1998).

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