Related topics: physical review letters

Macroscopic quantum phenomena discovered in ice

(Phys.org)—Scientists have discovered an anomaly in the properties of ice at very cold temperatures near 20 K, which they believe can be explained by the quantum tunneling of multiple protons simultaneously. The finding ...

Scientists view a quantum jump in real time

(PhysOrg.com) -- For more than two decades, scientists have been "watching" electrons in atoms make the jump between energy levels in real time. "Atoms have energy levels, and when electrons 'jump' from one level to another, ...

Does weak equivalence break down at the quantum level?

(PhysOrg.com) -- One of the givens in physics is the weak equivalence principle. This principle has been considered solid since Einstein proposed that it is not possible to detect the difference between uniform acceleration ...

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Perturbation theory (quantum mechanics)

In quantum mechanics, perturbation theory is a set of approximation schemes directly related to mathematical perturbation for describing a complicated quantum system in terms of a simpler one. The idea is to start with a simple system for which a mathematical solution is known, and add an additional "perturbing" Hamiltonian representing a weak disturbance to the system. If the disturbance is not too large, the various physical quantities associated with the perturbed system (e.g. its energy levels and eigenstates) can, from considerations of continuity, be expressed as 'corrections' to those of the simple system. These corrections, being 'small' compared to the size of the quantities themselves, can be calculated using approximate methods such as asymptotic series. We can therefore study the complicated system based on our knowledge of the simpler one.

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