Publications (47)
Multiple Schrödinger pictures and dynamics in shortcuts to adiabaticity
S. Ibáñez, Xi Chen, E. Torrontegui +2
A Schrödinger equation may be transformed by unitary operators into dynamical equations in different interaction pictures which share with it a common physical frame, i.e., the sa…
Shortcuts to adiabaticity in three-level systems using Lie transforms
S. MartÃnez-Garaot, E. Torrontegui, Xi Chen +1
Sped-up protocols (shortcuts to adiabaticity) that drive a system quickly to the same populations than a slow adiabatic process may involve Hamiltonian terms difficult to realize i…
Ultra-fast two-qubit ion gate using sequences of resonant pulses
E. Torrontegui, D. Heinrich, M. I. Hussain +2
We propose a new protocol to implement ultra-fast two-qubit phase gates with trapped ions using spin-dependent kicks induced by resonant transitions. By only optimizing the allocat…
Action-Noise-Assisted Quantum Control
Amikam Levy, E. Torrontegui, Ronnie Kosloff
We study the effect of action noise on state-to-state control protocols. Action noise creates dephasing in the instantaneous eigenbasis of the Hamiltonian and hampers the fidelity…
Unitary quantum perceptron as efficient universal approximator
E. Torrontegui, J. J. Garcia-Ripoll
We demonstrate that it is possible to implement a quantum perceptron with a sigmoid activation function as an efficient, reversible many-body unitary operation. When inserted in a…
Energy consumption for Shortcuts To Adiabaticity
E. Torrontegui, I. Lizuain, S. González-Resines +4
Shortcuts to adiabaticity let a system reach the results of a slow adiabatic process in a shorter time. We propose to quantify the "energy cost" of the shortcut by the energy consu…
Shortcuts to adiabaticity
E. Torrontegui, S. Ibáñez, S. MartÃnez-Garaot +6
Quantum adiabatic processes -that keep constant the populations in the instantaneous eigenbasis of a time-dependent Hamiltonian- are very useful to prepare and manipulate states, b…
Classical picture of post-exponential decay
E. Torrontegui, J. G. Muga, J. Martorell +1
Post-exponential decay of the probability density of a quantum particle leaving a trap can be reproduced accurately, except for interference oscillations at the transition to the p…
Quantum control of frequency tunable transmon superconducting qubits
J. J. GarcÃa-Ripoll, A. Ruiz-Chamorro, E. Torrontegui
In this work we analyze the implementation of a control-phase gate through the resonance between the and states of two statically coupled transmons. We fi…
Hamiltonian engineering via invariants and dynamical algebra
E. Torrontegui, S. MartÃnez-Garaot, J. G. Muga
We use the dynamical algebra of a quantum system and its dynamical invariants to inverse engineer feasible Hamiltonians for implementing shortcuts to adiabaticity. These are speede…
Single-atom heat engine as a sensitive thermal probe
Amikam Levy, Moritz Göb, Bo Deng +3
We propose employing a quantum heat engine as a sensitive probe for thermal baths. In particular, we study a single-atom Otto engine operating in an open thermodynamic cycle. Owing…
Noise Resistant Quantum Control Using Dynamical Invariants
Amikam Levy, A. Kiely, J. G. Muga +2
A systematic approach to design robust control protocols against the influence of different types of noise is introduced. We present control schemes which protect the decay of the…
Speed-up Quantum Perceptron via Shortcuts to Adiabaticity
Yue Ban, Xi Chen, E. Torrontegui +2
The quantum perceptron is a fundamental building block for quantum machine learning. This is a multidisciplinary field that incorporates abilities of quantum computing, such as sta…
Shortcuts to adiabaticity: fast-forward approach
E. Torrontegui, S. MartÃnez-Garaot, A. Ruschhaupt +1
The "fast-forward" approach by Masuda and Nakamura generates driving potentials to accelerate slow quantum adiabatic dynamics. First we present a streamlined version of the formali…
Multi-GHz repetition rate, multi-watt average power, ultraviolet laser pulses for fast trapped-ion entanglement operations
M. I. Hussain, D. Heinrich, M. Guevara-Bertsch +4
The conventional approach to perform two-qubit gate operations in trapped ions relies on exciting the ions on motional sidebands with laser light, which is an inherently slow proce…
Detecting quantum backflow by the density of a Bose-Einstein Condensate
M. Palmero, E. Torrontegui, M. Modugno +1
Quantum backflow is a classically forbidden effect consisting in a negative flux for states with negligible negative momentum components. It has never been observed experimentally…
The quest for absolute zero in presence of external noise
E. Torrontegui, R. Kosloff
A reciprocating quantum refrigerator is analyzed with the intention to study the limitations imposed by external noise. In particular we focus on the behavior of the refrigerator w…
Fidelity bounds for spin-dependent kicks with pulsed lasers
C. Sagaseta, H. Liu, V. D. Vaidya +3
Excitation of trapped-ion hyperfine qubits with fast optical Raman pulses enables faster-than-trap-period entangling gates with qubits of long coherence time for practical quantum…
Tailored Ion Beam for Precise Color Center Creation
A. Tobalina, C. Munuera-Javaloy, E. Torrontegui +2
We present a unitary quantum control scheme that produces a highly monochromatic ion beam from a Paul trap. Our protocol is implementable by supplying the segmented electrodes with…
Optimal trajectories for efficient atomic transport without final excitation
Xi Chen, E. Torrontegui, Dionisis Stefanatos +2
We design optimal harmonic-trap trajectories to transport cold atoms without final excitation, combining an inverse engineering techniqe based on Lewis-Riesenfeld invariants with o…
Quantum neural networks with multi-qubit potentials
Yue Ban, E. Torrontegui, J. Casanova
We propose quantum neural networks that include multi-qubit interactions in the neural potential leading to a reduction of the network depth without losing approximative power. We…
Fast atomic transport without vibrational heating
E. Torrontegui, S. Ibáñez, Xi Chen +3
We use the dynamical invariants associated with the Hamiltonian of an atom in a one dimensional moving trap to inverse engineer the trap motion and perform fast atomic transport wi…
Enhanced observability of quantum post-exponential decay using distant detectors
E. Torrontegui, J. G. Muga, J. Martorell +1
We study the elusive transition from exponential to post-exponential (algebraic) decay of the probability density of a quantum particle emitted by an exponentially decaying source,…
Low resource entanglement classification from neural network interpretability
A. GarcÃa-Velo, R. Puebla, Y. Ban +2
Entanglement is a central resource in quantum information and quantum technologies, yet its characterization remains challenging due to both theoretical complexity and measurement…
Marginal second-order moments do not suffice for entanglement detection
A. GarcÃa-Velo, M. Paraschiv, Y. Ban +2
The complete knowledge of the global and marginal second-order moments of a quantum state is in general insufficient for entanglement detection. By deriving the conditions on local…
Realization of a quantum perceptron gate with trapped ions
P. Huber, J. Haber, P. Barthel +3
We report the implementation of a perceptron quantum gate in an ion-trap quantum computer. In this scheme, a perceptron's target qubit changes its state depending on the interactio…
Fast transport of Bose-Einstein condensates
E. Torrontegui, Xi Chen, M. Modugno +3
We propose an inverse method to accelerate without final excitation the adiabatic transport of a Bose Einstein condensate. The method, applicable to arbitrary potential traps, is b…
Invariant-based inverse engineering of time-dependent, coupled harmonic oscillators
A. Tobalina, E. Torrontegui, I. Lizuain +2
Two-dimensional systems with time-dependent controls admit a quadratic Hamiltonian modelling near potential minima. Independent, dynamical normal modes facilitate inverse Hamiltoni…
Vibrational mode multiplexing of ultracold atoms
S. MartÃnez-Garaot, E. Torrontegui, Xi Chen +4
Sending multiple messages on qubits encoded in different vibrational modes of cold atoms or ions along a transmission waveguide requires to merge first and then separate the modes…
Fast generation of spin-squeezed states in bosonic Josephson junctions
B. Juliá-DÃaz, E. Torrontegui, J. Martorell +2
We describe methods for fast production of highly coherent-spin-squeezed many-body states in bosonic Josephson junctions (BJJs). We start from the known mapping of the two-site Bos…
Shortcuts to adiabaticity: concepts, methods, and applications
D. Guéry-Odelin, A. Ruschhaupt, A. Kiely +3
Shortcuts to adiabaticity (STA) are fast routes to the final results of slow, adiabatic changes of the controlling parameters of a system. The shortcuts are designed by a set of an…
Shortcut to adiabaticity in internal bosonic Josephson junctions
A. Yuste, B. Juliá-DÃaz, E. Torrontegui +3
We extend a recent method to shortcut the adiabatic following to internal bosonic Josephson junctions in which the control parameter is the linear coupling between the modes. The a…
Fast transport of two ions in an anharmonic trap
M. Palmero, E. Torrontegui, D. Guéry-Odelin +1
We design fast trajectories of a trap to transport two ions using a shortcut-to-adiabaticity technique based on invariants. The effects of anharmonicity are analyzed first perturba…
Cold atom dynamics in crossed laser beam waveguides
E. Torrontegui, J. Echanobe, A. Ruschhaupt +2
We study the dynamics of neutral cold atoms in an -shaped crossed-beam optical waveguide formed by two perpendicular red-detuned lasers of different intensities and a blue-detun…
Fast transitionless expansions of cold atoms in optical Gaussian beam traps
E. Torrontegui, Xi Chen, M. Modugno +3
We study fast expansions of cold atoms in a three-dimensional Gaussian-beam optical trap. Three different methods to avoid final motional excitation are compared: inverse engineeri…
Enhancing polarization transfer from nitrogen-vacancy centers in diamond to external nuclear spins via dangling bond mediators
H. Espinós, C. Munuera-Javaloy, I. Panadero +4
The use of nitrogen-vacancy centers in diamond as a non-invasive platform for hyperpolarizing nuclear spins in molecular samples is a promising area of research with the potential…
Large Quantum Delocalization of a Levitated Nanoparticle using Optimal Control: Applications for Force Sensing and Entangling via Weak Forces
T. Weiss, M. Roda-Llordes, E. Torrontegui +2
We propose to optimally control the harmonic potential of a levitated nanoparticle to quantum delocalize its center-of-mass motional state to a length scale orders of magnitude lar…
Transient Non-Confining Potentials for Speeding Up a Single Ion Heat Pump
E. Torrontegui, S. T. Dawkins, M. Göb +1
We propose speeding up a single ion heat pump based on a tapered ion trap. If a trapped ion is excited in an oscillatory motion axially the radial degrees of freedom are cyclically…
Invariant-based inverse engineering of crane control parameters
S. González-Resines, D. Guéry-Odelin, A. Tobalina +3
By applying invariant-based inverse engineering in the small-oscillations regime, we design the time dependence of the control parameters of an overhead crane (trolley displacement…
Engineering fast and stable splitting of matter waves
E. Torrontegui, S. MartÃnez-Garaot, M. Modugno +2
When attempting to split coherent cold atom clouds or a Bose-Einstein condensate (BEC) by bifurcation of the trap into a double well, slow adiabatic following is unstable with resp…
Lewis-Riesenfeld invariants and transitionless tracking algorithm
Xi Chen, E. Torrontegui, J. G. Muga
Different methods have been recently put forward and implemented experimentally to inverse engineer the time dependent Hamiltonian of a quantum system and accelerate slow adiabatic…
Quantum simulation of a triatomic chemical reaction with ultracold atoms on a waveguide
E. Torrontegui, A. Ruschhaupt, D. Guéry-Odelin +1
We study the scaling and coordinate transformation to physically simulate quantum three-body collinear chemical reactions of the type A+BC AB+C by the motion of singl…
Activated and non activated dephasing demonstrated in NV center dynamics
E. Torrontegui, R. Kosloff
We analyze different decoherence processes in a system coupled to a bath. Apart from the well known standard dephasing mechanism which is temperature dependent an alternative mecha…
Single-ion optical autocorrelator
M. I. Hussain, M. Guevara-Bertsch, E. Torrontegui +3
Well isolated quantum systems are exquisite sensors of electromagnetic fields. In this work, we use a single trapped ion for characterizing chirped ultraviolet (UV) picosecond lase…
Shortcuts to adiabaticity for non-Hermitian systems
S. Ibáñez, S. MartÃnez-Garaot, Xi Chen +2
Adiabatic processes driven by non-Hermitian, time-dependent Hamiltonians may be sped up by generalizing inverse engineering techniques based on Berry's transitionless driving algor…
Explanation and observability of diffraction in time
E. Torrontegui, J. Muñoz, Yue Ban +1
Diffraction in time (DIT) is a fundamental phenomenon in quantum dynamics due to time-dependent obstacles and slits. It is formally analogous to diffraction of light, and is expect…
Modulated Continuous Wave Control for Energy-efficient Electron-nuclear Spin Coupling
J. Casanova, E. Torrontegui, M. B. Plenio +2
We develop energy efficient, continuous microwave schemes to couple electron and nuclear spins, using phase or amplitude modulation to bridge their frequency difference. These cont…