Many-particle entanglement in multiple quantum nuclear-magnetic-resonance spectroscopy
Serge I. Doronin, Edward B. Fel’dman, I. D. Lazarev · Physical Review A · 2019
We use multiple quantum (MQ) nuclear magnetic resonance dynamics of a gas of spin-carrying molecules in nanocavities at high and low temperatures for an investigation of many-particle entanglement. A distribution of MQ NMR intensities is obtained at high and low temperatures in a system of 201 spins $\frac{1}{2}$. The second moment of the distribution, which provides a lower bound on the quantum Fisher information, sheds light on the many-particle entanglement in the system. The dependence of the many-particle entanglement on the temperature is investigated. Almost all spins are entangled at low temperatures.