Demonstration of a Quantum Controlled-NOT Gate in the Telecommunications Band

Abstract

We present the first quantum controlled-not (cnot) gate realized using a fiber-based indistinguishable photon-pair source in the 1.55 microm telecommunications band. Using this free-space cnot gate, all four Bell states are produced and fully characterized by performing quantum-state tomography, demonstrating the gate's unambiguous entangling capability and high fidelity. Telecom-band operation makes this cnot gate particularly suitable for quantum-information-processing tasks that are at the interface of quantum communication and linear optical quantum computing.

High-efficiency superconducting nanowire single-photon detectors fabricated from MoSi thin-films

“…In addition to their high efficiencies, SNSPDs have also demonstrated fast recovery times (< 10 ns) [6][7][8][9], low jitter (< 100 ps) [10], and low intrinsic dark count rates (< 1 count per second, cps) [5]. SNSPDs are ideal detectors for demanding quantum optics experiments [11][12][13][14][15], as well as other applications such as long-distance ground-to-space optical communications [16], characterization of single-photon sources and photon pair sources [17,18], light detection and ranging (LIDAR) [19], distributed fiber sensing [20], and integrated circuit testing [21].…”

Characteristics of Correlated Photon Pairs Generated in Ultracompact Silicon Slow-Light Photonic Crystal Waveguides

“…For example, a photon-pair source can be used as a heralded single-photon source or as a polarization or time-bin entangled source [1]- [17]. This has motivated the development of photon-pair generation in silica optical fibers [1]- [7] with a view towards all-fiber quantum information systems [8]. In particular, for integrated quantum information processing, photon-pair generation has been demonstrated in a number of photonic chip platforms, such as crystalline and amorphous silicon nanowires [9]- [14], periodically poled LiNbO 3 (PPLN) [15] and LiTO 3 (PPLT) [16] waveguides, and chalcogenide waveguides [17].…”

“…For a given power consumption, the required path length of a nonlinear device can be significantly reduced if we can enhance the device nonlinearity. For example, in previous photon-pair generation experiments, the typical length of silica fibers was in the range 1-300 m due to the low silica nonlinearity and the weak optical confinement provided by the fibers [1]- [8], while the length of PPLN, PPLT and chalcogenide waveguides was reduced to a few centimeters [15]- [17]. The use of highly nonlinear silicon nanowires, where light is tightly confined down to the sub-micrometer scale, has been shown to enable decreases in the device length down to approximately 1 cm [9]- [14].…”

Quantum Strategies: Proposal to Experimentally Test a Quantum Economics Protocol

“…LOQC gates are inherently non-deterministic (this CNOT gate has a 1/9 probability of success); coupled with the general lack of high-efficiency telecom-band single photon counters, this dictates that adequate detection systems are a key experimental concern. Previous experiments [18] addressed this problem by using a single superconducting single-photon detector to herald an InGaAs/lnP photodiode with a gate rate of 0.8 MHz.…”