Improving few-photon optomechanical effects with coherent feedback

Abstract

Few-photon effects such as photon blockade and tunneling have potential applications in modern quantum technology. To enhance the few-photon effects in an optomechanical system, we introduce a coherent feedback loop to cavity mode theoretically. By studying the second-order correlation function, we show that the photon blockade effect can be improved with feedback. Under appropriate parameters, the photon blockade effect exists even when cavity decay rate is larger than the single-photon optomechanical coupling coefficient, which may reduce the difficulty of realizing single-photon source in experiments. Through further study of the third-order correlation function, we show that the tunneling effect can also be enhanced by feedback. In addition, we discuss the application of feedback on Schrödinger-cat state generation in an optomechanical system. The result shows that the fidelity of cat state generation can be improved in the presence of feedback loop.

Enhanced magnon blockade in a magnomechanical system

“…Under the weak driving condition, if |0〉 and |1〉 is resonant (i.e., Δ = Δ 0 ), there will be detuning 2Δ 0 between |1〉 and |2〉 (i.e., two-magnon offresonance), which makes the conventional single-magnon blockade possible. In the presence of dissipation, the energy level is broadened, which hurt the magnon blockade effect [41]. In our system, the two-magnon driving term will bring a direct two-magnon excitation pathway due to MPA, i.e.…”

“…Similar to photon blockade and phonon blockade [36][37][38][39][40][41][42][43][44][45][46][47], magnon blockade as a typical quantum phenomenon, will also play an important role in studying the characteristics of magnomechanical systems [14,[48][49][50][51][52]. For single-magnon blockade, its definition is exciting the first magnon in the system suppresses subsequent magnon excitations, resulting in the anti-bunching effect of magnons.…”

Mechanical resonator cooling to the ground-state by coherent feedback in a double cavity setup including an atomic ensemble

“…For the case r > 0, a portion (proportional to r) of the output of the optomechanical cavity is reflected to the input mirror. A similar coherent feedback scheme has been used to study quantum effects such as normal-mode splitting [51], photon blockade [57], and entanglement [58]. The Hamiltonian of the proposed feedback system can be written as:…”

The photon blockade in a three-wave mixing system coupled with a quantum dot

“…In 2005, the CPB was firstly observed in an optical cavity with a trapped atom [12]. Since then, more and more systems have been proposed to implement the CPB, such as quantum optomechanical systems [13][14][15][16][17][18][19][20][21], atomic cavity QED systems [22][23][24], doubly resonant nanocavities with second-order nonlinearity [25], and hybrid optomagnonic microcavity [26]. Another method to realize photon blockade is referred to the unconventional photon blockade (UPB).…”