Browsing by Author "Tame, Mark"

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    Demonstration of Shor’s factoring algorithm for N = 21 on IBM quantum processors
    (Nature, 2021-08-16) Skosana, Unathi; Tame, Mark
    We report a proof-of-concept demonstration of a quantum order-finding algorithm for factoring the integer 21. Our demonstration involves the use of a compiled version of the quantum phase estimation routine, and builds upon a previous demonstration. We go beyond this work by using a configuration of approximate Toffoli gates with residual phase shifts, which preserves the functional correctness and allows us to achieve a complete factoring of N=21 . We implemented the algorithm on IBM quantum processors using only five qubits and successfully verified the presence of entanglement between the control and work register qubits, which is a necessary condition for the algorithm’s speedup in general. The techniques we employ may be useful in carrying out Shor’s algorithm for larger integers, or other algorithms in systems with a limited number of noisy qubits.
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    Generation of a frequency-degenerate four-photon entangled state using a silicon nanowire
    (Nature Research, 2019) Feng, Lan-Tian; Zhang, Ming; Zhou, Zhi-Yuan; Chen, Yang; Li, Ming; Dai, Dao-Xin; Ren, Hong-Liang; Guo, Guo-Ping; Guo, Guang-Can; Tame, Mark; Ren, Xi-Feng
    Integrated photonics is becoming an ideal platform for generating two-photon entangled states with high brightness, high stability, and scalability. This high brightness and high quality of photon pair sources encourages researchers further to study and manipulate multiphoton entangled states. Here, we experimentally demonstrate frequency-degenerate four-photon entangled state generation based on a single silicon nanowire 1 cm in length. The polarization encoded entangled states are generated with the help of a Sagnac loop using additional optical elements. The states are analyzed using quantum interference and state tomography techniques. As an example, we show that the generated quantum states can be used to achieve phase super-resolution. Our work provides a method for preparing indistinguishable multi-photon entangled states and realizing quantum algorithms in a compact on-chip setting.