A 14 × 14 μm2 footprint polarization-encoded quantum controlled-NOT gate based on hybrid waveguide

Abstract

Photonic quantum information processing system has been widely used in communication, metrology and lithography. The recent emphasis on the miniaturized photonic platform is thus motivated by the urgent need for realizing large-scale information processing and computing. Although the integrated quantum logic gates and quantum algorithms based on path encoding have been successfully demonstrated, the technology for handling another commonly used polarization-encoded qubits has yet to be fully developed. Here, we show the implementation of a polarization-dependent beam-splitter in the hybrid waveguide system. With precisely design, the polarization-encoded controlled-NOT gate can be implemented using only single such polarization-dependent beam-splitter with the significant size reduction of the overall device footprint to 14 × 14 μm2. The experimental demonstration of the highly integrated controlled-NOT gate sets the stage to develop large-scale quantum information processing system. Our hybrid design also establishes the new capabilities in controlling the polarization modes in integrated photonic circuits.

Probing Decoherence in Plasmonic Waveguides in the Quantum Regime

“…These nanophotonic devices are important for emerging quantum technologies, such as photonic-based quantum computers [16,17] and quantum communication networks [18]. Following on from early work probing SPPs with quantum states of light, such as entangled photons [19], recent studies have demonstrated several key quantum applications, including quantum sensing and imaging [20][21][22][23][24], quantum spectroscopy [25], quantum logic gates [26], entanglement generation [27] and distillation [28], and quantum random number generation [29]. What is surprising is that all of these applications can be realized even in the presence of loss, which is always present in plasmonic systems as they are scaled down to confine light to smaller scales.…”

Quasi-phase-matched second harmonic generation of long-range surface plasmon polaritons

“…The perfect RI material for LRSPPs in this study is LiNbO 3 , so steam will be absorbed by its surface and the RI will increase. When the RI changes significantly, LRSPPs cannot be excited, because the frequency is beyond the cut-off frequency of LRSPPs [21].…”

“…Surface plasmon polaritons (SPPs) can transmit or manipulate signals at the sub-micrometer or nanometer scale at optical frequencies because of their inherent properties, enabling SPPs to have many potential applications in integrated optics. Several SPP photonic devices have been reported, such as plasmonic demultiplexers [1], Airy beams [2], and polarization-encoded quantum-controlled NOT gates [3]. In addition, new theories, concepts, and applications of SPPs have emerged, including SPP holography [4], SPP crystals [5], nano-antennae [6], and plasmonic metamaterials [7].…”

“…Because of the strong absorption of metals at optical frequencies, the SHG efficiency of LSPs is low and the typical transmission distance of the SHG of LSPs ranges from sub-micrometers to micrometers [13]. The size of integrated photonic devices/chips usually ranges from about tens of micrometers to millimeters [3]. Therefore, if we design nonlinear integrated photonic devices/chips based on the SHG of SPPs, the efficiency and transmission distance of SHGs should both improve greatly.…”

Effect of unbalanced and common losses in quantum photonic integrated circuits

“…By integrating the waveguides and controlling their coupling on a chip, basic optical elements [2] in bulk optics can be realized on-chip with high quality, such as beam splitter (BS), phase shifter and polarization beam splitter (PBS) [3,4] . Recently, quantum C-NOT gate, quantum walk and Boson sampling have been performed on a single chip, based on silica-on-silicon waveguides [5,6] , laser direct writing waveguides [7,8] and plasmonic waveguides [9,10] . While, there still remains challenges to integrate optical devices with good performance, and the errors due to experimental imperfection will be amplified when cascading many basic integrated devices together for future quantum computing, simulation and communication.…”