Entangled Photon Pair Source Demonstrator using the Quantum Instrumentation Control Kit System

We report the first demonstration of using the Quantum Instrumentation and Control Kit (QICK) system on RFSoCFPGA technology to drive an entangled photon pair source and to detect the photon signals. With the QICK system, we achieve high levels of performance metrics including coincidence-to-accidental ratio exceeding 150, and entanglement visibility exceeding 95%, consistent with performance metrics achieved using conventional waveform generators. We also demonstrate simultaneous detector readout using the digitization functional of QICK, achieving internal system synchronization time resolution of 3.2 ps. The work reported in this paper represents an explicit demonstration of the feasibility for replacing commercial waveform generators and time taggers with RFSoC-FPGA technology in the operation of a quantum network, representing a cost reduction of more than an order of magnitude

Teleportation Systems Toward a Quantum Internet

Quantum teleportation is essential for many quantum information technologies, including long-distance quantum networks. Using fiber-coupled devices, including state-of-the-art low-noise superconducting nanowire single-photon detectors and off-the-shelf optics, we achieve conditional quantum teleportation of time-bin qubits at the telecommunication wavelength of 1536.5 nm. We measure teleportation fidelities of ≥90% that are consistent with an analytical model of our system, which includes realistic imperfections. To demonstrate the compatibility of our setup with deployed quantum networks, we teleport qubits over 22 km of single-mode fiber while transmitting qubits over an additional 22 km of fiber. Our systems, which are compatible with emerging solid-state quantum devices, provide a realistic foundation for a high-fidelity quantum Internet with practical devices

Teleportation Systems Toward a Quantum Internet

Quantum teleportation is essential for many quantum information technologies, including long-distance quantum networks. Using fiber-coupled devices, including state-of-the-art low-noise superconducting nanowire single-photon detectors and off-the-shelf optics, we achieve conditional quantum teleportation of time-bin qubits at the telecommunication wavelength of 1536.5 nm. We measure teleportation fidelities of ≥90% that are consistent with an analytical model of our system, which includes realistic imperfections. To demonstrate the compatibility of our setup with deployed quantum networks, we teleport qubits over 22 km of single-mode fiber while transmitting qubits over an additional 22 km of fiber. Our systems, which are compatible with emerging solid-state quantum devices, provide a realistic foundation for a high-fidelity quantum Internet with practical devices

Picosecond Synchronization of Photon Pairs through a Fiber Link between Fermilab and Argonne National Laboratories

We demonstrate a three-node quantum network for C-band photon pairs using 2 pairs of 59 km of deployed fiber between Fermi and Argonne National Laboratories. The C-band pairs are directed to nodes using a standard telecommunication switch and synchronized to picosecond-scale timing resolution using a coexisting O- or L-band optical clock distribution system. We measure a reduction of coincidence-to-accidental ratio (CAR) of the C-band pairs from 51 $\pm$ 2 to 5.3 $\pm$ 0.4 due to Raman scattering of the O-band clock pulses. Despite this reduction, the CAR is nevertheless suitable for quantum networks

Bell state measurements for quantum communication

Over the last few decades, quantum key distribution (QKD) has gained a lot of attention due to its promise of establishing secret keys between authenticated users even in the presence of an eavesdropper who is only confined by the laws of nature. Secure key established by QKD in conjunction with one-time pad (OTP) encryption thus promises to end the long standing battle between code-makers and code-breakers. Spurred by its great promise, QKD has been the first quantum information technology to be commercialized and QKD systems are available from a number of vendors.However, these systems are still vulnerable to side-channel attacks as the components used in these systems don’t necessarily conform to the idealistic assumptions made in security proofs of QKD. Of the many components, single photon detectors have been identified as the most vulnerable component allowing, for instance, so-called ‘blinding attacks.’ In light of this, measurement device independent quantum key distribution (MDIQKD) protocol was proposed as a means to make QKD inherently immune to all possible detector side channel attacks, due to the particular property of the so-called Bell state measurement. The aim of this thesis is to develop techniques that will allow developing a cost- effective MDIQKD system that is suitable for quantum networks and to use these techniques to perform quantum teleportation on a metropolitan scale for the first time. More precisely this thesis describes the assessment of performance of MDIQKD using differ- ent hardware; the development of cost-effective MDIQKD system for quantum networks; the building of a practical quantum random generator (QRNG) suitable for high speed QKD systems; the demonstration of quantum teleportation on a metropolitan scale and the realization of an efficient Bell state analyzer for time-bin qubits that improves the efficiency of all quantum information processing tasks including MDIQKD and quantum teleportation. The above demonstrations constitute an important step towards realizing practical quantum internet

Small-form-factor Gaussian-modulated coherent-state transmitter for CV-QKD using a gain-switched DFB laser

We report a directly modulated distributed feedback laser operating in gain-switching mode for preparing the coherent states required for the Gaussian-modulated coherent-state (GMCS) continuous-variable quantum key distribution (CV-QKD) protocol. The proposed single-component quantum transmitter design eliminates the need for external modulators, decreasing the complexity of GMCS CV-QKD systems. The experimental results demonstrate a potential asymptotic secret key rate value of 2.63 Mbps over an 11-km fiber link, making the directly modulated GMCS transmitter particularly suitable for metropolitan optical networks where compactness, robustness, and low cost are key desirable features