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The development of compact plasma accelerators, enabled by the advent of high-power lasers, could revolutionize the use of particle beams. This review presents the physical principles that underlie such devices and provides an outlook on the possibilities.
A collection of bosonic particles, such as liquid helium or ultracold gases, can condense into a ground state in which the atoms flow as a ‘superfluid’ without scattering. Magnetic materials further illustrate the generality of the effect, as described in this review.
At a zero-temperature phase transition from one ordered state to another, fluctuations between the two states lead to quantum critical behaviour that can lead to unexpected physics. Metals with ‘heavy’ electrons often harbour such weird states.
Quantum magnetism describes systems of magnetic spins in which quantum mechanical effects dominate, often in surprising ways. This review article covers phase transitions between these states, including quantum criticality and entangled electron states.
