Limits...
A simple and general strategy for generating frequency-anticorrelated photon pairs.

Zhang X, Xu C, Ren Z - Sci Rep (2016)

Bottom Line: To reduce the required flux, a promising solution is to use highly frequency-anticorrelated photon pairs, which are known to induce two-photon transitions much more efficiently.It is shown quantitatively that this strategy can generate highly frequency-anticorrelated photon pairs which can dramatically enhance two-photon excitation efficiency.We believe the proposed strategy can guide new designs for generating frequency-anticorrelated photon pairs.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210008, China.

ABSTRACT
Currently, two-photon excitation microscopy is the method of choice for imaging living cells within thick specimen. A remaining problem for this technique is the damage caused by the high photon flux in the excitation region. To reduce the required flux, a promising solution is to use highly frequency-anticorrelated photon pairs, which are known to induce two-photon transitions much more efficiently. It is still an open question what the best scheme is for generating such photon pairs. Here we propose one simple general strategy for this task. As an example, we show explicitly that this general strategy can be realized faithfully within the widely applicable coherently pumped Jaynes-Cummings model. It is shown quantitatively that this strategy can generate highly frequency-anticorrelated photon pairs which can dramatically enhance two-photon excitation efficiency. We believe the proposed strategy can guide new designs for generating frequency-anticorrelated photon pairs.

No MeSH data available.


Related in: MedlinePlus

Realization of the proposed general strategy in the coherently pumped JC model.The proposed general strategy (cf. Fig. 1) can be realized faithfully in the coherently pumped JC model in the strong coupling - strong detuning - strong pumping regime. The levels drawn are the eigenstates /±n〉(n = 0, 1, 2) of the zeroth-order Hamiltonian (equation (2)). The initial state /−0〉 is coupled through the weak effective coupling to /+2〉, which decays quickly through single-photon emission to /+1〉, which decays quickly through single-photon emission to the stable state /+0〉. These match precisely with the proposed strategy. Note that this level scheme is drawn within the interaction picture of the laser (cf. equation (1)), and thus the energy scales are not in the optical domain but on the scale of (cf. equation (3)) the difference frequencies δTLS, δcav and the Rabi frequency of the laser Ω. Within the large detuning - strong pumping regime as considered here, the two-photon resonance condition between /−0〉 and /+2〉 as shown can always be met by tuning δcav via changing the resonance frequency of the cavity (cf. equation (3)).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4834487&req=5

f4: Realization of the proposed general strategy in the coherently pumped JC model.The proposed general strategy (cf. Fig. 1) can be realized faithfully in the coherently pumped JC model in the strong coupling - strong detuning - strong pumping regime. The levels drawn are the eigenstates /±n〉(n = 0, 1, 2) of the zeroth-order Hamiltonian (equation (2)). The initial state /−0〉 is coupled through the weak effective coupling to /+2〉, which decays quickly through single-photon emission to /+1〉, which decays quickly through single-photon emission to the stable state /+0〉. These match precisely with the proposed strategy. Note that this level scheme is drawn within the interaction picture of the laser (cf. equation (1)), and thus the energy scales are not in the optical domain but on the scale of (cf. equation (3)) the difference frequencies δTLS, δcav and the Rabi frequency of the laser Ω. Within the large detuning - strong pumping regime as considered here, the two-photon resonance condition between /−0〉 and /+2〉 as shown can always be met by tuning δcav via changing the resonance frequency of the cavity (cf. equation (3)).

Mentions: Now we only need to verify that this effective Hamiltonian indeed correctly describes the dynamics of the TLS-cavity system. We show in Fig. 3 for the typical parameter combination studied in this paper a comparison between the predictions given by the original Hamiltonian (equation (1)) and those given by this effective Hamiltonian (equation (4)) in the presence of cavity decay. In the figure we plot the evolutions of the occupation-probabilities for four states: /+0〉, /+1〉, /+2〉 and /−0〉. As can be seen, for all the four states the two curves to be compared are essentially indistinguishable. Thus the effective Hamiltonian describes the system dynamics correctly. To sum up, the proposed strategy “” can be realized faithfully using the coherently pumped JC model to be “” by working in the strong coupling - large detuning - strong pumping regime and tuning the state /−0〉 and /+2〉 to be near degenerate. The realized scenario is depicted schematically in Fig. 4.


A simple and general strategy for generating frequency-anticorrelated photon pairs.

Zhang X, Xu C, Ren Z - Sci Rep (2016)

Realization of the proposed general strategy in the coherently pumped JC model.The proposed general strategy (cf. Fig. 1) can be realized faithfully in the coherently pumped JC model in the strong coupling - strong detuning - strong pumping regime. The levels drawn are the eigenstates /±n〉(n = 0, 1, 2) of the zeroth-order Hamiltonian (equation (2)). The initial state /−0〉 is coupled through the weak effective coupling to /+2〉, which decays quickly through single-photon emission to /+1〉, which decays quickly through single-photon emission to the stable state /+0〉. These match precisely with the proposed strategy. Note that this level scheme is drawn within the interaction picture of the laser (cf. equation (1)), and thus the energy scales are not in the optical domain but on the scale of (cf. equation (3)) the difference frequencies δTLS, δcav and the Rabi frequency of the laser Ω. Within the large detuning - strong pumping regime as considered here, the two-photon resonance condition between /−0〉 and /+2〉 as shown can always be met by tuning δcav via changing the resonance frequency of the cavity (cf. equation (3)).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834487&req=5

f4: Realization of the proposed general strategy in the coherently pumped JC model.The proposed general strategy (cf. Fig. 1) can be realized faithfully in the coherently pumped JC model in the strong coupling - strong detuning - strong pumping regime. The levels drawn are the eigenstates /±n〉(n = 0, 1, 2) of the zeroth-order Hamiltonian (equation (2)). The initial state /−0〉 is coupled through the weak effective coupling to /+2〉, which decays quickly through single-photon emission to /+1〉, which decays quickly through single-photon emission to the stable state /+0〉. These match precisely with the proposed strategy. Note that this level scheme is drawn within the interaction picture of the laser (cf. equation (1)), and thus the energy scales are not in the optical domain but on the scale of (cf. equation (3)) the difference frequencies δTLS, δcav and the Rabi frequency of the laser Ω. Within the large detuning - strong pumping regime as considered here, the two-photon resonance condition between /−0〉 and /+2〉 as shown can always be met by tuning δcav via changing the resonance frequency of the cavity (cf. equation (3)).
Mentions: Now we only need to verify that this effective Hamiltonian indeed correctly describes the dynamics of the TLS-cavity system. We show in Fig. 3 for the typical parameter combination studied in this paper a comparison between the predictions given by the original Hamiltonian (equation (1)) and those given by this effective Hamiltonian (equation (4)) in the presence of cavity decay. In the figure we plot the evolutions of the occupation-probabilities for four states: /+0〉, /+1〉, /+2〉 and /−0〉. As can be seen, for all the four states the two curves to be compared are essentially indistinguishable. Thus the effective Hamiltonian describes the system dynamics correctly. To sum up, the proposed strategy “” can be realized faithfully using the coherently pumped JC model to be “” by working in the strong coupling - large detuning - strong pumping regime and tuning the state /−0〉 and /+2〉 to be near degenerate. The realized scenario is depicted schematically in Fig. 4.

Bottom Line: To reduce the required flux, a promising solution is to use highly frequency-anticorrelated photon pairs, which are known to induce two-photon transitions much more efficiently.It is shown quantitatively that this strategy can generate highly frequency-anticorrelated photon pairs which can dramatically enhance two-photon excitation efficiency.We believe the proposed strategy can guide new designs for generating frequency-anticorrelated photon pairs.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210008, China.

ABSTRACT
Currently, two-photon excitation microscopy is the method of choice for imaging living cells within thick specimen. A remaining problem for this technique is the damage caused by the high photon flux in the excitation region. To reduce the required flux, a promising solution is to use highly frequency-anticorrelated photon pairs, which are known to induce two-photon transitions much more efficiently. It is still an open question what the best scheme is for generating such photon pairs. Here we propose one simple general strategy for this task. As an example, we show explicitly that this general strategy can be realized faithfully within the widely applicable coherently pumped Jaynes-Cummings model. It is shown quantitatively that this strategy can generate highly frequency-anticorrelated photon pairs which can dramatically enhance two-photon excitation efficiency. We believe the proposed strategy can guide new designs for generating frequency-anticorrelated photon pairs.

No MeSH data available.


Related in: MedlinePlus