Photon-spin Quantum Media Conversion via Teleportation in diamond
Ryota Kuroiwa a, Yuhei Sekiguchi a, Naeko Niikura a, Joerg Wrachtrupb and Hideo Kosaka a,*a
Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, JAPANb
Physikalisches Institut, Research Center SCOPE, and MPI for Solid State Research,
University of Stuttgart, Pfaenwaldring 57, 70569 Stuttgart, Germany
E-mail: kosaka@ynu.ac.jp
Quantum information is carried on various kinds of quantum media such as photons,electrons, and nucleus in the basis of polarization or spin states [1, 2]. Photons transfer aquantum state over long distance, while nuclear spins store a quantum state for long time [3].
Quantum media conversion between them will be required as an interface for hybrid quantum
systems. The promising way to achieve deterministic quantum media conversion is to use thequantum teleportation scheme, which utilizes a prepared electron-nucleus entanglement andpost-selection of photon-electron entanglement [4]. The redundancy is required to distil lessfrequent event into only the success event with the help of quantum non-demolition
measurement, which makes probabilistic process into deterministic. Without thepost-selection mechanism, we have to make not only a perfect optical cavity but also a perfect
optical link to suppress the inevitable photon loss that lowers the conversion fidelity.
We here report the experimental demonstration of quantum media conversion from a
photon to a nuclear spin by preparing an entangled state between an electron spin and anuclear spin, and successive photon absorption in diamond. The demonstration relies on themeasurement of an entangled state between the photon polarization and the electron spin
through the previously demonstrated entangled absorption [4]. The entangled absorption
utilizes an electronic orbital exited state which is entangled with the spin state to selectphotons whose polarization state corresponds to the spin state to absorb. Another importantmechanism is the quantum non-demolition measurement called the single-shot measurementof an electron spin state by spin-dependent photoluminescence measurement, which
post-selects only the success event without destroying the stored nuclear spin state to makeprobabilistic conversion into deterministic without any optical cavity.
Figure 1 shows the fidelity of the nuclear spin state transferred from the photon
polarization state. The fidelity of the conversion is over 90%, which enough exceeds theclassical limit of 50%. Although we used a photon ensemble for the input to speed up themeasurement, the averaged photon number to be absorbed is less than one and the scheme isindependent of photon number even well below one since the distillation mechanism is built
in the scheme.
We thank Sen Yang, Helmut Fedder, Ali Momenzadeh Seyed, Norikazu Mizuochi for
their discussions and experimental
supports. This work was supported by theNICT Quantum Repeater Project, by theFIRST Quantum Information Project, andby a Grant-in-Aid for Scientific Research(A)-JSPS (No. 24244044).
[1] H. Kosaka, et. al., Phys. Rev. Lett. 100,096602 (2008).
[2] H. Kosaka, et.al., Nature 457,702–705 (2009).
[3] Y. Sekiguchi, et. al., Nature Commun.
in press.
[4] H. Kosaka & N. Niikura, Phys. Rev.
Lett. 114, 053603 (2015).

Fig. 1: Conditional probability oftransferred states from a photon
polarization state to a nuclear spinstate.