No abstract
We report the first experimental generation and characterization of a six-photon Dicke state. The produced state shows a fidelity of F = 0.56 ± 0.02 with respect to an ideal Dicke state and violates a witness detecting genuine six-qubit entanglement by four standard deviations. We confirm characteristic Dicke properties of our resource and demonstrate its versatility by projecting out four-and five-photon Dicke states, as well as four-photon GHZ and W states. We also show that Dicke states have interesting applications in multiparty quantum networking protocols such as opendestination teleportation, telecloning and quantum secret sharing. In this Letter we report the experimental generation and investigation of a variety of multi-photon entangled states. We present a flexible linear-optics setup that can produce four-, five-and six-photon representatives of the important class of Dicke states, as well as four-photon GHZ states. Information is encoded in the polarization degrees of freedom of entangled photons produced by high-order spontaneous parametric down conversion (SPDC). We show that our generated states are genuinely multipartite entangled by using tailormade and experimentally favorable witness tools. These new characterization methods are important in virtue of the non-ideal nature of the six-photon state: although spurious nonlinear processes affect its quality, quantum features can still be observed and characterized. We also highlight the potential for quantum control in large Hilbert spaces by evaluating protocols such as telecloning, open-destination teleportation and quantum secret sharing [11,12,13,14,15].Experiment.- Fig. 1 (a) shows the setup for the generation of the three-excitation six-photon Dicke state |D (3) 6 = 1 √ 20 P |HHHV V V 123456 . Here, |H/V i are horizontal/vertical polarization states of a photon in spatial mode i = 1, .., 6, which encode the logical states of a qubit, while P denotes the sum over all permutations of logical states [16]. In the setup, six photons are probabilistically distributed among the spatial modes by nonpolarizing beamsplitters (BSs): upon detecting one photon in each mode we post-selectively observe |D (3) 6. We use higher-order emissions of a collinear type-II SPDC process for the simultaneous production of three pairs of photons [17]. A Coherent Inc. Verdi V-18 laser is combined with a mode-locked Mira HP Ti:Sa oscillator to reach the energy necessary to observe third-order SPDC emissions. The pulsed-laser output (τ = 200 fs, λ = 810 nm, 76 MHz) is frequency-doubled using a 2 mmthick Lithium triborate (LBO) crystal, resulting in UV pulses of 1.4 W cw-average. To avoid optical damage to the anti-reflection coating of the LBO, we continuously translate it with a step-motor, achieving a very stable source of UV pulses (power and count-rate fluctuations less than 1 − 2% over 30 h). The UV pulses are focused onto a 2 mm-thick β-barium borate (BBO) type-II crystal, cut for collinear down-conversion emission. Dichroic mirrors then separate the down-converted...
Multipartite entangled states are a fundamental resource for a wide range of quantum information processing tasks. In particular, in quantum networks, it is essential for the parties involved to be able to verify if entanglement is present before they carry out a given distributed task. Here we design and experimentally demonstrate a protocol that allows any party in a network to check if a source is distributing a genuinely multipartite entangled state, even in the presence of untrusted parties. The protocol remains secure against dishonest behaviour of the source and other parties, including the use of system imperfections to their advantage. We demonstrate the verification protocol in a three- and four-party setting using polarization-entangled photons, highlighting its potential for realistic photonic quantum communication and networking applications.
We provide the quantum-mechanical description of the excitation of surface plasmon polaritons on metal surfaces by single photons. An attenuated-reflection setup is described for the quantum excitation process in which we find remarkably efficient photon-to-surface plasmon wave-packet transfer. Using a fully quantized treatment of the fields, we introduce the Hamiltonian for their interaction and study the quantum statistics during transfer with and without losses in the metal.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.