Extended Data Fig. 2: Full experiment sequence.
From: Spin squeezing in an ensemble of nitrogen–vacancy centres in diamond
(a) The experiment consists of three parts: lattice engineering, squeezing generation, and squeezing readout. (b) In the lattice engineering step, we prepare an effective lattice from the disordered system by removing NV dimers with either the shelving method (i) or the depolarization method (ii). (c) To generate squeezing, we evolve the system under its native dipolar interactions HXXZ for a time tg. (d) In the readout step, we first apply a pulse with variable rotation angle θ along the x axis (yellow) to map the spin operator Sθ into Sz. Then we probe the variance Var(Sθ) by measuring the quench dynamics of the rotated squeezed state for a time tr. The initial and final π/2 pulses that initialize and readout the state on + x axis are shown in black. Throughout the time evolution, we apply XY-8 pulses to decouple the Ising interaction between NV and P1 centers. We conclude the experiment by a fluorescence readout while shining the 532 nm laser (not shown).
