High-fidelity quantum driving

Bason, M. G.; Viteau, Matthieu; Malossi, Nicola; Huillery, Paul; Arimondo, E.; Ciampini, Donatella; Fazio, Rosario; Giovannetti, Vittorio; Mannella, R.; Morsch, O.

doi:10.1038/nphys2170

Cited by 459 publications

(526 citation statements)

References 27 publications

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“…(iii) θ has to be determined from Eq. (13). (iv) The fast-forward potential can be calculated from Eq.…”

Section: Connection With the Fast-forward Approachmentioning

confidence: 99%

“…Among other approaches let us mention (i) a transitionless tracking algorithm or "counterdiabatic" approach that adds to the original Hamiltonian extra terms to cancel transitions in the adiabatic or superadiabatic bases [8][9][10][11][12][13]; (ii) inverse engineering of the external driving [3,4,6,[21][22][23][24][25][26] based on Lewis-Riesenfeldt invariants [27], which has been applied in several expansion experiments [25,26]; (iii) optimal control (OC) methods [5,7,14,16], sometimes combined with other methods to enhance their performance [4,5,7]; (iv) the fast-forward (FF) approach advocated by Masuda and Nakamura [19,28]; (v) parallel adiabatic passage [29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

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Shortcuts to adiabaticity: Fast-forward approach

et al. 2012

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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 formalism that produces the main results in a few steps. Then we show the connection between this approach and inverse engineering based on Lewis-Riesenfeld invariants. We identify in this manner applications in which the engineered potential does not depend on the initial state. Finally we discuss more general applications exemplified by wave splitting processes.

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“…(iii) θ has to be determined from Eq. (13). (iv) The fast-forward potential can be calculated from Eq.…”

Section: Connection With the Fast-forward Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Shortcuts to adiabaticity: Fast-forward approach

et al. 2012

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“…In particular the Chopped Random Basis (CRAB) technique offers an efficient way to implement optimal control, based on an expansion of the control field onto a truncated basis [14,15]. Recently it has been shown that optimal control allows for reaching the Quantum Speed Limit (QSL), the minimal time required by physical constraints to perform a given transformation, in spin chains [19,20], cold atoms in optical lattices [21], Bose-Einstein condensates in atom chip experiments and in crossing of quantum phase transitions [23]. Indeed, CRAB control makes it possible to reduce the time of the transformation down to the QSL, which scales as 1/∆, obtaining a quadratic speedup of the protocol with re- spect to the adiabatic one.…”

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confidence: 99%

Noise-resistant optimal spin squeezing via quantum control

et al. 2016

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Entangled atomic states, such as spin squeezed states, represent a promising resource for a new generation of quantum sensors and atomic clocks. We demonstrate that optimal control techniques can be used to substantially enhance the degree of spin squeezing in strongly interacting many-body systems, even in the presence of noise and imperfections. Specifically, we present a protocol that is robust to noise which outperforms conventional methods. Potential experimental implementations are discussed.PACS numbers: 42.50. Dv, 02.30.Yy, 32.80.Qk Spin squeezed states are among the most interesting examples of entangled states. In quantum metrology they allow for measurements with an improved precision, ultimately limited only by the Heisenberg limit. Since the early theoretical proposals to realize them with non linear interactions [2,3], spin squeezed states have been implemented in several experiments. Specific examples include generation of spin squeezed states in cavity QED [4][5][6], in trapped ions through shared motional modes [7,8] or using a Bose-Einstein condensate [9,10].In this Letter we demonstrate that optimal control can be effectively employed to produce highly squeezed spin states in many-body quantum systems, drastically reducing the impact of relaxation and decoherence. Other approaches applied control techniques creating spin squeezing as a succession of unitary pulses of a constant Hamiltonian [11][12][13]. We employ the Chopped Random Basis (CRAB) technique [14,15] to optimally control the evolution of a collection of N two-level systems mutually coupled through a time-dependent non linear (i.e. quadratic) interaction. linear (i.e. quadratic) interaction. We calculate optimized evolutions occurring on time scales several orders of magnitude shorter than the corresponding adiabatic evolutions, with a speed-up increasing with the system size. Such a speed-up translates directly into an enhanced robustness of the squeezing in the presence of noise, as schematically depicted in Fig. 1. We illustrate this enhanced robustness by modelling two practical experimental implementations of squeezed state preparations: cavity QED and trapped ions [6,8].We will focus on two methods realizing spin squeezed states, both with advantages in different situations. The first is based on the so called one-axis twisting protocol, consisting in letting a collection of two-level systems evolve under the effect of a collective non linear interaction [3], described by a Hamiltonian of the formWhere ω is the precession frequency and χ is the strength of the nonlinear interaction and J is a collective spin operator (defined below). The relative simplicity of the one-axis twisting scheme has been at the basis of its ubiquitous presence in squeezing experiments; however such a scheme is known to be non optimal [3], the spherical nature of the angular momentum phase space limiting the maximal squeezing achievable. Such a bound is intrinsic for the one-axis twisting protocol with fixed χ. It nevertheless allows to achieve spi...

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“…The second scheme we consider is the CP protocol [25]. This scheme has been proved to be capable to control a system described by a LZ-type Hamiltonian at the maximum speed allowed by quantum mechanics [24,26].…”

Section: B Efficiency and Speed Of Control Protocols For Csd Navigationmentioning

confidence: 99%

“…These various control strategies include the use of analytically wellestablished phenomena like the paradigmatic LandauZener (LZ) transition [12][13][14], Landau-Zener-Stückelberg interferometry [15,16], the composite pulse (CP) protocol and several other two-level control strategies [12,[24][25][26][27], and OCT [18][19][20][21][22][23]. For the experimental control strategies, as can be seen in [10,[15][16][17], the first stage is the measurement of the charge stability diagram (CSD).…”

Section: Introductionmentioning

confidence: 99%

Controlled high-fidelity navigation in the charge stability diagram of a double quantum dot

Coden¹,

Romero²,

Räsänen³

2015

J. Phys.: Condens. Matter

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We propose an efficient control protocol for charge transfer in a double quantum dot. We consider numerically a two-dimensional model system, where the quantum dots are subjected to timedependent electric fields corresponding to experimental gate voltages. Our protocol enables navigation in the charge stability diagram from a state to another through controllable variation of the fields. We show that the well-known adiabatic Landau-Zener transition -when supplemented with a time-dependent field tailored with optimal control theory -can remarkably improve the transition speed. The results also lead to a simple control scheme that requires only a single parameter obtained from the experimental charge stability diagram. Eventually, we can control the system at the fastest speed allowed by the quantum dynamics and with a high fidelity.

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High-fidelity quantum driving

Cited by 459 publications

References 27 publications

Shortcuts to adiabaticity: Fast-forward approach

Shortcuts to adiabaticity: Fast-forward approach

Noise-resistant optimal spin squeezing via quantum control

Controlled high-fidelity navigation in the charge stability diagram of a double quantum dot

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