Enhancing Spin-Phonon and Spin-Spin Interactions Using Linear Resources in a Hybrid Quantum System

Abstract

Hybrid spin-mechanical setups offer a versatile platform for quantum science and technology, but improving the spin-phonon as well as the spin-spin couplings of such systems remains a crucial challenge.Here, we propose and analyze an experimentally feasible and simple method for exponentially enhancing the spin-phonon and the phonon-mediated spin-spin interactions in a hybrid spin-mechanical setup, using only linear resources. Through modulating the spring constant of the mechanical cantilever with a time-dependent pump, we can acquire a tunable and nonlinear (two-phonon) drive to the mechanical mode, thus amplifying the mechanical zero-point fluctuations and directly enhancing the spin-phonon coupling. This method allows the spin-mechanical system to be driven from the weak-coupling regime to the strong-coupling regime, and even the ultrastrong coupling regime. In the dispersive regime, this method gives rise to a large enhancement of the phonon-mediated spin-spin interactions between distant solid-state spins, typically two orders of magnitude larger than that without modulation. As an example, we show that the proposed scheme can apply to generating entangled states of multiple spins with high fidelities even in the presence of large dissipations.

Adiabatic preparation of maximum entanglement in hybrid quantum systems with the Z 2 symmetry

“…To deal with this major obstacle well, two different major routes of this scheme are further considered at here. For the first route, as illustrated in Figure 6(A,B), we can also further enhance the density of the magnetic fields through fabricating a number of nanotubes (with N nanotubes) together instead of single nanotube 33,55 . With the given parameters above for single nanotube, we also estimate the effective coupling approximately and plot the relevant expected results in Figure 6(C).…”

“…In this dressed‐state basis, NV's energy‐level diagram is illustrated in Figure 1(C), the parameters and are both adjustable, and we can get the suitable energy level which is comparable with the frequency of the nanotube 11,32,33 . According to Figure 1(C), we can rewrite the Hamiltonian under this new basis, where the parameters are expressed as , , , and …”

“…To exhibit the basic physical mechanism more clearly, we first demonstrate this adiabatic evolution process for ideal condition by setting , here, the fidelity for the quantum states of the final ground states is expressed as 33,51,53,54 . And plot the comparison of the dynamical fidelity in Figures 3 and 4.…”

Experimental quantum simulation of superradiant phase transition beyond no-go theorem via antisqueezing

“…Let us first experimentally demonstrate the antisqueezing-enhanced ZPF in our 4-spin system, which is the key physical mechanism of recovering ground-state SPT in the case of including the A 2 term. It is also the nature of antisqueezing-enhanced light-matter interaction explored in recent theoretical [39][40][41][42][43][44][45] and experimental 46 works. Theoretically, the antisqueezing term ĤAs will make the ground state of an oscillator from a vacuum state 0 j i to the squeezed vacuum state ŜðrÞ 0 j i with ŜðrÞ ¼ exp½rðâ 2 À ây2 Þ=2 and the squeezing parameter r ¼ ð1=4Þln ð1 À 4ξ=ωÞ.…”

“…These states could be used for faulttolerant quantum computation 34,35 and quantum metrology 36 approaching the Heisenberg limit, aside from providing fundamental insights into the nature of decoherence and the quantumclassical transition 37 . Our work also provides the important family of antisqueezing with a new type of applications, besides widely known ones in quantum precision measurement 38 and enhancing light-matter interaction [39][40][41][42][43][44][45][46] .…”