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Ivette Fuentes

Publications and source records attributed to Ivette Fuentes.

At least 73 records · Page 4Linked to original sources

Relativistic Quantum Metrology: Exploiting relativity to improve quantum measurement technologies

We present a framework for relativistic quantum metrology that is useful for both Earth-based and space-based technologies. Quantum metrology has been so far successfully applied to design precision instruments such as clocks and sensors which outperform classical devices by exploiting quantum properties. There are advanced plans to implement these and other quantum technologies in space, for instance Space-QUEST and Space Optical Clock projects intend to implement quantum communications and quantum clocks at regimes where relativity starts to kick in. However, typical setups do not take into account the effects of relativity on quantum properties. To include and exploit these effects, we introduce techniques for the application of metrology to quantum field theory. Quantum field theory properly incorporates quantum theory and relativity, in particular, at regimes where space-based experiments take place. This framework allows for high precision estimation of parameters that appear in quantum field theory including proper times and accelerations. Indeed, the techniques can be applied to develop a novel generation of relativistic quantum technologies for gravimeters, clocks and sensors. As an example, we present a high precision device which in principle improves the state-of-the-art in quantum accelerometers by exploiting relativistic effects.

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Spacetime effects on satellite-based quantum communications

We investigate the consequences of space-time being curved on space-based quantum communication protocols. We analyze tasks that require either the exchange of single photons in a certain entanglement distribution protocol or beams of light in a continuous-variable quantum key distribution scheme. We find that gravity affects the propagation of photons, therefore adding additional noise to the channel for the transmission of information. The effects could be measured with current technology.

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Quantum parameter estimation with imperfect reference frames

Quantum metrology studies quantum strategies which enable us to outperform their classical counterparts. In this framework, the existence of perfect classical reference frames is usually assumed. However, such ideal reference frames might not always be available. The reference frames required in metrology strategies can either degrade or become misaligned during the estimation process. We investigate how the imperfectness of reference frames leads to noise which in general affects the ultimate precision limits in measurement of physical parameters. Moreover, since quantum parameter estimation can be phrased as a quantum communication protocol between two parties, our results provide deeper insight into quantum communication protocols with misaligned reference frames. Our framework allows for the study of general noise on the efficiency of such schemes.

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Ruling out stray thermal radiation in analogue black holes

Experimental searches for the thermal radiation from analogue black holes require the measurement of very low temperatures in regimes where other thermal noises may interfere or even mimic the sought-after effect. In this letter, we parameterize the family of bosonic thermal channels which give rise to such thermal effects and show that by use of coherent states and homodyne detection one can rule out the non-Hawking contributions and identify those candidate sources which arise from Hawking-like processes.

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Gravitational parameter estimation in a waveguide

We investigate the intrinsic uncertainty in the accuracy to which a static spacetime can be measured from scattering experiments. In particular, we focus on the Schwarzschild black hole and a spatially kinked metric that has some mathematical resemblance to an expanding universe. Under selected conditions we find that the scattering problem can be framed in terms of a lossy bosonic channel, which allows us to identify shot-noise scaling as the ultimate scaling-limit to the estimation of the spacetimes. Fock state probes with particle counting measurements attain this ultimate scaling limit and the scaling constants for each spacetime are computed and compared to the practical strategies of coherent state probes with heterodyne and homodyne measurements. A promising avenue to analyze the quantum-limit of the analogue spacetimes in optical waveguides is suggested.

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Voyage to Alpha Centauri: Entanglement degradation of cavity modes due to motion

We propose a scheme to investigate whether non-uniform motion degrades entanglement of a relativistic quantum field that is localised both in space and in time. For a Dirichlet scalar field in a cavity in Minkowski space, in small but freely-adjustable acceleration of finite but arbitrarily long duration, degradation of observable magnitude occurs for massless transverse quanta of optical wavelength at Earth gravity acceleration and for kaon mass quanta already at microgravity acceleration. We outline a space-based experiment for observing the effect and its gravitational counterpart.

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Quantum metrology for relativistic quantum fields

In quantum metrology quantum properties such as squeezing and entanglement are exploited in the design of a new generation of clocks, sensors and other measurement devices that can outperform their classical counterparts. Applications of great technological relevance lie in the precise measurement of parameters which play a central role in relativity, such as proper accelerations, relative distances, time and gravitational field strengths. In this paper we generalise recently introduced techniques to estimate physical quantities within quantum field theory in flat and curved space-time. We consider a bosonic quantum field that undergoes a generic transformation, which encodes the parameter to be estimated. We present analytical formulas for optimal precision bounds on the estimation of small parameters in terms of Bogoliubov coefficients for single mode and two-mode Gaussian channels.

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On the robustness of entanglement in analogue gravity systems

We investigate the possibility to generate quantum-correlated quasi-particles utilizing analogue gravity systems. The quantumness of these correlations is a key aspect of analogue gravity effects and their presence allows for a clear separation between classical and quantum analogue gravity effects. However, experiments in analogue systems, such as Bose-Einstein condensates, and shallow water waves, are always conducted at non-ideal conditions, in particular, one is dealing with dispersive media at nonzero temperatures. We analyze the influence of the initial temperature on the entanglement generation in analogue gravity phenomena. We lay out all the necessary steps to calculate the entanglement generated between quasi-particle modes and we analytically derive an upper bound on the maximal temperature at which given modes can still be entangled. We further investigate a mechanism to enhance the quantum correlations. As a particular example we analyze the robustness of the entanglement creation against thermal noise in a sudden quench of an ideally homogeneous Bose-Einstein condensate, taking into account the super-sonic dispersion relations.

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Relativistic Motion Generates Quantum Gates and Entanglement Resonances

We show that the relativistic motion of a quantum system can be used to generate quantum gates. The nonuniform acceleration of a cavity is used to generate well-known two-mode quantum gates in continuous variables. Observable amounts of entanglement between the cavity modes are produced through resonances which appear by repeating periodically any trajectory.

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Mode-mixing quantum gates and entanglement without particle creation in periodically accelerated cavities

We show that mode-mixing quantum gates can be produced by non-uniform relativistic acceleration. Periodic motion in cavities exhibits a series of resonant conditions producing entangling quantum gates between different frequency modes. The resonant condition associated with particle creation is the main feature of the dynamical Casimir effect which has been recently demonstrated in superconducting circuits. We show that a second resonance, which has attracted less attention since it implies negligible particle production, produces a beam splitting quantum gate leading to a resonant enhancement of entanglement which can be used as the first evidence of acceleration effects in mechanical oscillators. We propose a desktop experiment where the frequencies associated with this second resonance can be produced mechanically.

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Time evolution techniques for detectors in relativistic quantum information

The techniques employed to solve the interaction of a detector and a quantum field typically require perturbation methods. We introduce mathematical techniques to solve the time evolution of an arbitrary number of detectors interacting with a quantum field. Our techniques apply to harmonic oscillator detectors and can be generalized to treat detectors modeled by quantum fields. Since the interaction Hamiltonian we introduce is quadratic in creation and annihilation operators, we are able to draw from continuous variable techniques commonly employed in quantum optics.

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Relativistic Quantum Teleportation with Superconducting Circuits

We study the effects of relativistic motion on quantum teleportation and propose a realizable experiment where our results can be tested. We compute bounds on the optimal fidelity of teleportation when one of the observers undergoes non-uniform motion for a finite time. The upper bound to the optimal fidelity is degraded due to the observer's motion however, we discuss how this degradation can be corrected. These effects are observable for experimental parameters that are within reach of cutting-edge superconducting technology. Our setup will further provide guidance for future space-based experiments.

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Quantum gates and multipartite entanglement resonances realized by non-uniform cavity motion

We demonstrate the presence of genuine multipartite entanglement between the modes of quantum fields in non-uniformly moving cavities. The transformations generated by the cavity motion can be considered as multipartite quantum gates. We present two setups for which multi-mode entanglement can be generated for bosons and fermions. As a highlight we show that the bosonic genuine multipartite correlations can be resonantly enhanced. Our results provide fundamental insights into the structure of Bogoliubov transformations and suggest strong links between quantum information, quantum fields in curved spacetimes and gravitational analogs by way of the equivalence principle.

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Observer dependent entanglement

Understanding the observer-dependent nature of quantum entanglement has been a central question in relativistic quantum information. In this paper we will review key results on relativistic entanglement in flat and curved spacetime and discuss recent work which shows that motion and gravity have observable effects on entanglement between localized systems.

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Entanglement generation in relativistic quantum fields

We present a general, analytic recipe to compute the entanglement that is generated between arbitrary, discrete modes of bosonic quantum fields by Bogoliubov transformations. Our setup allows the complete characterization of the quantum correlations in all Gaussian field states. Additionally, it holds for all Bogoliubov transformations. These are commonly applied in quantum optics for the description of squeezing operations, relate the mode decompositions of observers in different regions of curved spacetimes, and describe observers moving along non-stationary trajectories. We focus on a quantum optical example in a cavity quantum electrodynamics setting: an uncharged scalar field within a cavity provides a model for an optical resonator, in which entanglement is created by non-uniform acceleration. We show that the amount of generated entanglement can be magnified by initial single-mode squeezing, for which we provide an explicit formula. Applications to quantum fields in curved spacetimes, such as an expanding universe, are discussed.

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Particle and anti-particle bosonic entanglement in non-inertial frames

We analyse the entanglement tradeoff between particle and anti-particle modes of a charged bosonic field between inertial and uniformly accelerated observers. In contrast with previous results for fermionic fields, we find that the entanglement redistribution between particle and antiparticle modes does not prevent the entanglement from vanishing in the infinite acceleration limit.

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Motion generates entanglement

We demonstrate entanglement generation between mode pairs of a quantum field in a nonuniformly accelerated cavity in Minkowski space-time. The effect is sensitive to the initial state, the choice of the mode pair and bosonic versus fermionic statistics, and it can be stronger by orders of magnitude than the entanglement degradation between a nonuniformly accelerated cavity and an inertial cavity. Detailed results are obtained for massless scalar and spinor fields in (1+1) dimensions. By the equivalence principle, the results provide a model of entanglement generation by gravitational effects.

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Probing the spacetime structure of vacuum entanglement

We introduce a framework for probing the spacetime structure of vacuum entanglement that exhibits infinite range correlations between the future and the past, as well as spatially separated regions. Our results are non-perturbative and analytical.

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