Laser phase noise （LPN） plays an important role in optical coherent systems. Based on the algorithm of Viterbi-Viterbi cartier phase estimation （CPE）, the effects of LPN imposed on the coherent receivers are inves...Laser phase noise （LPN） plays an important role in optical coherent systems. Based on the algorithm of Viterbi-Viterbi cartier phase estimation （CPE）, the effects of LPN imposed on the coherent receivers are investigated for quadrature phase shift keying （QPSK）, 8 phase shift keying （SPSK） and 16-quadrature amplitude modulation （16-QAM） optical coherent systems, respectively. The simulation results show that the optimal block length in the phase estimation algorithm is a tradeoffbetween LPN and additive white Gaussian noise （AWGN）, and depends on the level of modulation formats. The resolution requirements of analog to digital converter （ADC） in the coherent receivers are independent of LPN or the level of modulation formats. For the bit error rate （BER） of 10-3, the required bit number of ADC is 6, and the gain is marginal for the higher resolution.展开更多
We propose a scheme for realizing an unconventional three-qubit controlled-phase gate via the Rydberg blockade mechanism.The qubit is encoded by atomic ensembles that are trapped in optical traps and fixed on an atom ...We propose a scheme for realizing an unconventional three-qubit controlled-phase gate via the Rydberg blockade mechanism.The qubit is encoded by atomic ensembles that are trapped in optical traps and fixed on an atom chip.Because of the collective nature of the encoding and the Rydberg blockade mechanism,the scheme do not require separate addressing of individual atoms.The time needed for the gate operation is much shorter than that in a similar scheme.In addition,we show the gate can be used as a basic tool for effective generation of large-scale 2D cluster states.展开更多
基金supported by the Scientific Research Program Funded by Shaanxi Provincial Education Department (No.11JK1006)
文摘Laser phase noise （LPN） plays an important role in optical coherent systems. Based on the algorithm of Viterbi-Viterbi cartier phase estimation （CPE）, the effects of LPN imposed on the coherent receivers are investigated for quadrature phase shift keying （QPSK）, 8 phase shift keying （SPSK） and 16-quadrature amplitude modulation （16-QAM） optical coherent systems, respectively. The simulation results show that the optimal block length in the phase estimation algorithm is a tradeoffbetween LPN and additive white Gaussian noise （AWGN）, and depends on the level of modulation formats. The resolution requirements of analog to digital converter （ADC） in the coherent receivers are independent of LPN or the level of modulation formats. For the bit error rate （BER） of 10-3, the required bit number of ADC is 6, and the gain is marginal for the higher resolution.
基金supported by the National Natural Science Foundation of China (Grant Nos.61275215 and 11004033)the Natural Science Foundation of Fujian Province (Grant No.2010J01002)the National Fundamental Research Program of China (Grant No.2011CBA00203)
文摘We propose a scheme for realizing an unconventional three-qubit controlled-phase gate via the Rydberg blockade mechanism.The qubit is encoded by atomic ensembles that are trapped in optical traps and fixed on an atom chip.Because of the collective nature of the encoding and the Rydberg blockade mechanism,the scheme do not require separate addressing of individual atoms.The time needed for the gate operation is much shorter than that in a similar scheme.In addition,we show the gate can be used as a basic tool for effective generation of large-scale 2D cluster states.
