量子力学模拟的新系统

Researchers from the universities in Mainz, Frankfurt, Hamburg and Ulm have proposed a new platform for quantum simulation. In a theoretical paper recently published in Physical Review Letters, they show that a combined system of ultracold trapped ions and fermionic（费米子） atoms could be used to emulate¹ solid state physics. This system may outperform possibilities of existing platforms as a number of phenomena² found in solid state systems are naturally included, such as the fermionic statistics of the electrons and the electron-sound wave interactions. Quantum simulation was first proposed by Richard Feynman in 1982. He realized that a calculation of quantum systems is well beyond the ability of any existing computer technology. This is because quantum mechanics features superpositions and entanglement³; its dynamics⁴ follows many pathways simultaneously⁵. Even the most powerful classical computers lack the computing⁶ power to keep track of all those possible outcomes even for small quantum systems. Feynman proposed using an easily accessible and easily controllable laboratory quantum system to mimic⁷ the quantum system of interest. This idea is reminiscent（怀旧的） to using a crash test dummy⁸ to simulate the dynamics of a collision in the classical world.   In their recent paper, the authors calculate that an ion crystal and a degenerate⁹ Fermi gas mimic a solid state system built up of atomic cores and electrons, making it a quantum simulator of such a system. The researchers show that a phase transition from a conducting to an insulating state can occur in their solid state look-alike. This unexpected many-body quantum effect is known as the Peierls transition and relies on lattice phonons and the fermionic statistics of the atoms. The authors expect that the system could be further expanded to study for instance phonon-mediated atom-atom interactions, thus simulating the phonon-mediated electron-electron interactions responsible for superconductivity.