Classical and Quantum Surface Plasmon Resonance Biosensing

Figure 9

LoD for different quantum states with respect to the angle of incidence. The purple line is two-mode product squeezed state (TPS is a quantum state but does not give a good LoD for this experiment), the orange line is an entangled quantum state called the NOON state (it is not a good quantum state for this type of sensing but is good for phase-sensing experiments), the green line is two-mode squeezed vacuum state (TMSV is a quantum state which performs just as well as the coherent state for this type of sensing), the black line is the twin coherent state (TMC, in this case, is the baseline for the best classical state performance), and the red line is two-mode Fock state (TMF is a quantum state which has the best LoD in this case, and it far outperforms all the other states). It is clear that the Fock state gives the better enhancement since the LoD is the lowest; thus, we can see that quantum states can outperform classical states such as the coherent state, justifying the need for quantum biosensors to enhance precision in SPR-based biosensors. This was taken from reference [40].