arXiv:2101.02117

Heralded hybrid CV-DV entanglement generation by quantum interference between CV state and DV delocalized photon

Sergey A. Podoshvedov, Nguyen Ba An

Published Jan 6, 2021• 1 citation

Abstract

Hybrid entangled states prove to be necessary for quantum information processing within heterogeneous quantum networks. A method with irreducible number of consumed resources that firmly provides hybrid CV-DV entanglement for any input conditions of the experimental setup is proposed. Namely, a family of CV states is introduced. Each of such CV states is first superimposed on a beam-splitter with a delocalized photon and then detected by a photo-detector behind the beam-splitter. Detection of any photon number heralds generation of a hybrid CV-DV entangled state in the outputs, independent of transmission/reflection coefficients of the beam-splitter and size of the input CV state. Nonclassical properties of the generated state are studied and their entanglement degree in terms of negativity is calculated. There are wide domains of values of input parameters of the experimental setup that can be chosen to make the generated state maximally entangled. The proposed method is also applicable to truncated versions of the input CV states. We also propose a simple method to produce even/odd CV states.

DOI: 10.48550/arxiv.2101.02117

Related papers

Universal DV-CV interaction mechanism for deterministic generation of entangled hybridity

Mikhail S. Podoshvedov, Sergey A. Podoshvedov

We propose a general approach for deterministic generation of the entangled hybrid states consisting of continuous variable (CV) and discrete variable (DV) states. Peculiarity of the interaction of DV and CV states on the beam splitter (BS) is key for the birth of the entangled hybridity provided that some measurement event is registered in auxiliary mode. We show that the CV states forming the output entangled state consist exclusively of either even or odd Fock states. Various input CV states, including the Schrödinger cat state, are tested at the input of the BS, where they mix with delocalized single photons. We show the hybrid entanglement generation is observed at arbitrary values of the experimental parameters used. The degree of the hybrid entanglement is evaluated. Conditions for generating the maximally entangled hybrid states are established.

arXiv:1909.13068Journal of the Optical Society of America BJan 17, 20203 citations

Family of even/odd CV states, their properties and deterministic generation of the hybrid entangled states

Evgeny V. Mikheev, Sergey A. Podoshvedov

We consider a family of continuous variable (CV) states being a superposition of displaced number states with equal modulo but opposite in sign displacement amplitudes. Either an even or odd CV state is mixed with a delocalized photon at a beam splitter with arbitrary transmittance and reflectance coefficients with the subsequent registration of the measurement outcome in an auxiliary mode to deterministically generate hybrid entanglement. We show that at certain values of the experimental parameters maximally entangled states are generated. The considered approach is also applicable to truncated finite versions of even/odd CV states. We study the nonclassical properties of the introduced states and show their Wigner functions exhibit properties inherent to nonclassical states. Other nonclassical properties of the states under consideration have also been studied.

arXiv:2008.03011Aug 7, 20200 citations

Entanglement synthesis based on the interference of a single-mode squeezed vacuum and a delocalized photon

Sergey A. Podoshvedov, Mikhail S. Podoshvedov

We propose a new approach to generate entangled states, both hybrid and consisting exclusively of continuous variable (CV) states. A single-mode squeezed vacuum is mixed with a delocalized single photon on an arbitrary beam splitter with subsequent registration of measurement outcomes in auxiliary mode. The entangled hybrid states consisting of CV and discrete variable (DV) states are generated whenever any event is measured in auxiliary mode. Negativity is used as a measure of entanglement. Under certain initial conditions, the conditional state becomes as entangled as possible. New types of CV states, either even or odd depending on the parity of the Fock states forming the superpositions, are introduced. If the conditional entangled hybrid state is mixed with a single-mode squeezed vacuum with the subsequent registration of measurement results in DV mode, then the new state becomes CV entangled, i.e., its orthogonal components are already CV states. The entanglement synthesis can be expanded to implement a high-complexity quantum network.

Journal of the Optical Society of America BMar 2, 202113 citations

Hybrid CV-DV Quantum Communications and Quantum Networks

Ivan B. Djordjević

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 variable-discrete 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 entanglement-based hybrid QKD.

IEEE AccessJan 1, 202219 citations

Entangled states shaping with CV states of definite parity

Dmitry Kuts, Sergey A. Podoshvedov

We present a new method to entangle continuous variable (CV) states of certain parity and photonic states for the purpose of generating optical hybrid cluster (HC) states. To do it we introduce two families of the CV states of definite parity which stems from single mode squeezed vacuum (SMSV) state. Potential to apply the CV states of certain parity is high. We report on the generation of the even/odd Schrödinger cat state like (SCS-like) states whose fidelities with even/odd SCS of amplitude of [Formula: see text] are more of [Formula: see text], when 30,31 photons are detected in auxiliary mode of input SMSV state initially mixed with single photon. We show that the quantum efficiency of a photon number resolving (PNR) detector is crucial to maintaining the success rate of even/odd SCSs generator at an acceptable level. The scheme with delocalized photon implements deterministic imperfect entanglement operation between macro and micro states. We show that the beam splitter implements the two-qubits operation [Formula: see text] (CZ) for input CV states of definite parity and photonic states, provided that certain result is detected in measurement mode. An extension of the entangling operation for two entangled delocalized photons (TEDP) allows one to realize three-qubit HC state. Seven-qubit HC state is the result of conjunction of two three-qubit HC states through TEDP state.

Scientific ReportsJan 28, 20226 citations

Beam splitters as controlled-Z gate for hybrid state

Mikhail S. Podoshvedov, Sergey A. Podoshvedov

We explore a scheme based on adding a nonlocal photon and subtracting some number of photons to entangle the initial single-mode squeezed vacuum (SMSV) state with the photon state. In a realistic model of interaction of the SMSV state with the photonic state on a beam splitter (BS) with changeable transmissivity or reflectivity the hybrid entanglement is realized for any values of the squeezing of input SMSV state. Maximum hybrid entanglement is achieved at certain values of the squeezing and BS parameter, which can mean implementation of a two-qubit controlled-Z (CZ-) operation using the BS with the appropriate initialization of the input states. The success probability of the gate, taking into account multiphoton outcomes in the measuring mode of the BS, is more than 0.3. We also propose to use new continuous variable (CV) states of definite parity that could increase the success probability of generating maximal hybrid entanglement. We show sufficient robustness of the generated entanglement under photon number resolving detection with practical quantum efficiency.

arXiv:2502.13463Feb 19, 20250 citations