=Paper= {{Paper |id=Vol-1482/538 |storemode=property |title=Optimized diamond photonic molecule for quantum communications |pdfUrl=https://ceur-ws.org/Vol-1482/538.pdf |volume=Vol-1482 }} ==Optimized diamond photonic molecule for quantum communications== https://ceur-ws.org/Vol-1482/538.pdf 
    Суперкомпьютерные дни в России 2015 // Russian Supercomputing Days 2015 // RussianSCDays.org



                      Optimized diamond photonic molecule
                          for quantum communications
                         M. S. Rogachev1,2, I.Yu. Kateev1, A.V. Tsukanov1
  Institute of Physics and Technology, Russian Academy of Sciences1, Moscow Institute of
                            Physics and Technology, Dolgoprudny2

     In recent years, elementary quantum optical structures, called photonic molecules (PMs), have
been carefully studied both experimentally and theoretically [1, 2]. There structures are formed from
high quality factor solid-state microresonators (MR). These devices may be integrated with single-
photon sources that generate and guide photon flows in a system and high-sensitivity detectors that fix
the arrival of a photon and, preferably, its polarization [3]. As for the element base for quantum com-
putation, the main effort of scientists is now focused on the search for the optimal geometry of a solid-
state photonic chip [4]. Here, we propose the design of three-unit PM optimized to obtain good
transport and dissipation properties.
     To design PM supporting optical-band frequencies, one uses photon cells with geometric dimen-
sions on the order of a few microns. MRs supporting whispering gallery modes (e.g. microrings) can
form quasi-one-dimensional optical structures. We optimize diamond microring parameters calculat-
ing the eigenfrequencies and the electrical field distributions of the single microring in a broad range
of inner and outer radii as well as thicknesses.
     Analytical consideration of the PM-system composed of three MRs is given within the formalism
of tight-binding phenomenological Hamiltonian:

                                                                                      
                                   3                        2
                             H   k  i k  ak ak   J k ,k 1 ak ak 1  ak1ak ,               (1)
                                  k 1                     k 1

where k is the mode frequency of the k-th MR (k = 1 – 3), ak and ak are creation and annihilation
operators of photons, respectively, J k , k 1 is a coefficient of photon hopping between the MRs,  k is a
rate of energy dissipation of the MR mode. Provided that k   and J k ,k 1  J each mode of the sin-
gle MR splits into three ones of PM with frequencies PM 1,3    2 J , PM 2   . The electric field
profile of PM for the eigenfrequencies PM 1,3 has antinodes located along the edge of each ring.
      The most common mean for controlling the dynamics of photons in PM is laser. Here we employ
the weak laser as a probe for the PM’s spectrum. The probability of one-photon excitation of PM due
to laser photon injection is calculated in the steady-state regime. The transmission spectrum was repre-
sented by a small number of clearly distinguishable peaks. As the MRs approach each other, the split-
ting of the peaks increases. It is very desirable to have equal optical field amplitudes in each resonator
for some eigenmode of the PM. Our solution consists in following choice of Hamiltonian parameters:
Jk,k+1  J, 1  3   , 2    J . In this case, the mode with the frequency PM ,opt    J is equally-
weighted: opt   1  2  3  3 .

References
1. Tsukanov A. V. Quantum dots in photonic molecules and quantum informatics. Part. I // Russian
   Microelectronics. 2013. Vol. 42. P. 325.
2. Tsukanov A. V. Quantum dots in photonic molecules and quantum informatics. Part. II // Russian
   Microelectronics. 2014. Vol. 43. P. 165.
3. Yariv A., Xu Y., Lee R. K. and Scherer A. Coupled resonator optical waveguide: a proposal and
   analysis // Opt. Lett. 1999. Vol. 24. P. 711.
4. Tsukanov A., Kateev I., Orlikovsky A. Quantum register based on structured diamond waveguide
   with NV centers // Proc. SPIE. 2012. Vol. 8700. P. 87001F.


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