Hybrid CV-DV Quantum Communications and Quantum Networks

Abstract

Quantum information processing (QIP) opens new opportunities for high-performance computing, high-precision sensing, and secure communications. Among various QIP features, the entanglement is a unique one. To take full advantage of quantum resources, it will be necessary to interface quantum systems based on different encodings of information both discrete and continuous. The goal of this paper is to lay the groundwork for the development of a robust and efficient hybrid continuous variablediscrete variable (CV-DV) quantum network, enabling the distribution of a large number of entangled states over hybrid DV-CV multi-hop nodes in an arbitrary topology. The proposed hybrid quantum communication network (QCN) can serve as the backbone for a future quantum Internet, thus providing extensive long-term impacts on the economy and national security through QIP, distributed quantum computing, quantum networking, and distributed quantum sensing. By employing the photon addition and photon subtraction modules we describe how to generate the hybrid DV-CV entangled states and how to implement their teleportation and entanglement swapping through entangling measurements. We then describe how to extend the transmission distance between nodes in hybrid QCN by employing macroscopic light states, noiseless amplification, and reconfigurable quantum LDPC coding. We further describe how to enable quantum networking and distributed quantum computing by employing the deterministic cluster state concept introduced here. Finally, we describe how the proposed hybrid CV-DV states can be used in an entanglementbased hybrid QKD.

Classical Coherent States Based Quantum Information Processing and Quantum Computing Analogs

“…Therefore, we have already introduced the concepts relevant in quantum mechanics such as the superposition principle (13), the completeness relationship (14), and the change of basis (15), while manipulating the classical polarization states. Now we describe how to entangle classical coherent states [1], [25]. The coherent state |, where  is a complex number [that is =||exp(j)], can be represented in terms of number (Fock) states |n as follows [17], [23]:…”

“…2 of ref. [25], we can entangle two continuous variable (CV) states with the help of two periodically polled lithium niobate (PPLN) crystals or waveguides serving the role of singlephoton addition modules. The corresponding circuit to entangle two coherent states | and |, based on Figs.…”

“…The quantum information processing (QIP) [1]- [25] is a very active research area with large number of applications including quantum computing [5]- [19], quantum communications [20]- [23], quantum networks [23]- [25], and quantum sensing [23], [26], to mention few. Further, significant efforts have been made towards the commercialization of quantum computers [27]- [29].…”

“…In the same section, we explain how to entangle coherent states based on refs. [1] and [25]. In Sec.…”

Nonclassicality of entangled Schrödinger cat states associated to generalized displaced Fock states

“…It is well known that the entangled states of light, as a fundamental resource, discover basic questions in quantum physics and have received many practical applications in quantum information processing including quantum communications [1][2][3][4], quantum computation [5], and quantum sensing [6]. Among these states, continuous variables entangled states, which have experimentally been generated by means of two independent squeezed [7] as well as coherent fields [8], and optical parametric amplifiers [9], are of great interest.…”