Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Remarkable advancements in the ability to create, manipulate, and measure quantum systems are paving the way to build next generations of devices based on quantum physics. Quantum technologies in Russia are on the list of strategically important cross-cutting directions in the framework of the National Technology Initiative programs and the Digital Economy National Program. The broad focus includes quantum computing and simulation, quantum communications, quantum metrology and sensing. This paper reviews existing research on quantum science and technologies in Russia and summarizes the main goals for the next few years that form the basis of an upcoming major national initiative.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The UK has, through a mix of government and industry funding, committed more than £1Bn over ten years to a coordinated programme in quantum technology. Five years into this programme, the UK National Quantum Technology Programme has induced a step change in the nation’s capabilities for establishing a new sector in future quantum information technologies. We describe how the programme arose and the activities it has supported and influenced to deliver these new capabilities, building on a first phase of over £385M investment across several UK government agencies. As the programme enters its second phase, with a further substantial investment by UK government and global industries, we review the prospects for ensuring the advanced quantum science and demonstrator platforms in imaging, sensing, timing, communications and computing developed over the past five years drive the formation of the sector and embed quantum tech in a broad range of industries by means of new products and services.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The possibility for quantum and classical communication to coexist on the same fiber is important for deployment and widespread adoption of quantum key distribution (QKD) and, more generally, a future quantum internet. While coexistence has been demonstrated for different QKD implementations, a comprehensive investigation for measurement-device independent (MDI) QKD—a recently proposed QKD protocol that cannot be broken by quantum hacking that targets vulnerabilities of single-photon detectors—is still missing. Here we experimentally demonstrate that MDI-QKD can operate simultaneously with at least five 10 Gbps bidirectional classical communication channels operating at around 1550 nm wavelength and over 40 km of spooled fiber, and we project communication rates in excess of 10 THz when moving the quantum channel from the third to the second telecommunication window. The similarity of MDI-QKD with quantum repeaters suggests that classical and generalized quantum networks can co-exist on the same fiber infrastructure.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this paper I propose a new method of encoding discrete variables into Ising model qubits for quantum optimisation. The new method is based on the physics of domain walls in one-dimensional Ising spin chains. I find that these encodings and the encoding of arbitrary two variable interactions is possible with only two body Ising terms Following on from similar results for the ‘one hot’ method of encoding discrete variables (Hadfield <jats:italic>et al</jats:italic> 2019 <jats:italic>Algorithms </jats:italic> <jats:bold>12</jats:bold> 34) I also demonstrate that it is possible to construct two body mixer terms which do not leave the logical subspace, an important consideration for optimising using the quantum alternating operator ansatz. I additionally discuss how, since the couplings in the domain wall encoding only need to be ferromagnetic and therefore could in principle be much stronger than anti-ferromagnetic couplers, application specific quantum annealers for discrete problems based on this construction may be beneficial. Finally, I compare embedding for synthetic scheduling and colouring problems with the domain wall and one hot encodings on two graphs which are relevant for quantum annealing, the chimera graph and the Pegasus graph. For every case I examine I find a similar or better performance from the domain wall encoding as compared to one hot, but this advantage is highly dependent on the structure of the problem. For encoding some problems, I find an advantage similar to the one found by embedding in a Pegasus graph compared to embedding in a chimera graph.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Entanglement is a key resource in quantum information science and associated emerging technologies. Photonic systems offer a large range of exploitable entanglement degrees of freedom (DOF) such as frequency, time, polarization, and spatial modes. Hyperentangled photons exploit multiple DOF simultaneously to enhance the performance of quantum information protocols. Here, we report a fully guided-wave approach for generating polarization and energy-time hyperentangled photons at telecom wavelengths. Moreover, by demultiplexing the broadband emission spectrum of the source into five standard telecom channel pairs, we demonstrate compliance with fibre network standards and improve the effective bit rate capacity of the quantum channel up to one order of magnitude. In all channel pairs, we observe a violation of a generalised Bell inequality by more than 27 standard deviations, underlining the relevance of our approach.</jats:p>