Quantum process tomography by 2D fluorescence spectroscopy

Pachón, Leonardo A.; Marcus, Andrew H.; Aspuru‐Guzik, Alán

doi:10.1063/1.4919954

Cited by 21 publications

(27 citation statements)

References 46 publications

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“…[11] This experimental technique is also used for the tomography of quantum states. [12] We suggestt hat the same kind of information can be measured using aS TM by electrical addressing of dopant molecules.…”

Section: Introductionmentioning

confidence: 96%

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Implementation of Multivariable Logic Functions in Parallel by Electrically Addressing a Molecule of Three Dopants in Silicon

et al. 2017

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To realize low‐power, compact logic circuits, one can explore parallel operation on single nanoscale devices. An added incentive is to use multivalued (as distinct from Boolean) logic. Here, we theoretically demonstrate that the computation of all the possible outputs of a multivariate, multivalued logic function can be implemented in parallel by electrical addressing of a molecule made up of three interacting dopant atoms embedded in Si. The electronic states of the dopant molecule are addressed by pulsing a gate voltage. By simulating the time evolution of the non stationary electronic density built by the gate voltage, we show that one can implement a molecular decision tree that provides in parallel all the outputs for all the inputs of the multivariate, multivalued logic function. The outputs are encoded in the populations and in the bond orders of the dopant molecule, which can be measured using an STM tip. We show that the implementation of the molecular logic tree is equivalent to a spectral function decomposition. The function that is evaluated can be field‐programmed by changing the time profile of the pulsed gate voltage.

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Section: Introductionmentioning

confidence: 96%

“…Optical experimental set ups based on nonlinear optical response allow following dynamically the time evolution of the coherences . This experimental technique is also used for the tomography of quantum states . We suggest that the same kind of information can be measured using a STM by electrical addressing of dopant molecules.…”

Section: Introductionmentioning

confidence: 99%

Implementation of Multivariable Logic Functions in Parallel by Electrically Addressing a Molecule of Three Dopants in Silicon

et al. 2017

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“…These dynamics are usually studied with non-linear ultrafast optical spectroscopy, allowing for the investigation of the underlying processes in exciton energy transport (EET). Two-dimensional electronic spectroscopy (2DES) is sufficient to perform full tomography of the quantum process of excitonic dynamics within the singly-excited manifold of light-harvesting complexes [7] and determine the precise values of the populations -as well as any quantum coherences between energy eigenstates [8][9][10][11][12] at the end of a dynamical process transforming any initial excited state. Unfortunately, it is known that this reconstruction can be non-unique [12,13].…”

Section: Introductionmentioning

confidence: 99%

Towards a spectroscopic protocol for unambiguous detection of quantum coherence in excitonic energy transport

2020

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The role of quantum effects in excitonic energy transport (EET) has been scrutinised intensely and with increasingly sophisticated experimental techniques. This increased complexity requires invoking correspondingly elaborate models to fit spectroscopic data before molecular parameters can be extracted. Possible quantum effects in EET can then be studied, but the conclusions are strongly contingent on the efficacy of the fitting and the accuracy of the model. To circumvent this challenge, we propose a witness for quantum coherence in EET that can be extracted directly from two-pulse pump-probe spectroscopy experimental data. We provide simulations to judge the feasibility of our approach. Somewhat counterintuitively, our protocol does not probe quantum coherence directly, but only indirectly through its implicit deletion. It allows for classical models with no quantum coherence to be decisively ruled out. arXiv:1905.06453v1 [quant-ph]

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“…Such inference is known as quantum process tomography (QPT). QPT has been performed in many different physical settings [2][3][4][5]: the challenge is producing an estimate of the process in a reasonable amount of time which matches the data as closely as possible and is consistent with a quantum mechanical model of the experiment. We present algorithms for reconstructing the process subject to appropriate constraints, via a subroutine that implements a composite projection onto the set of quantum channelssee Fig 1b. In Sec.…”

Section: Introductionmentioning

confidence: 99%

Quantum process tomography via completely positive and trace-preserving projection

et al. 2018

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We present an algorithm for projecting superoperators onto the set of completely positive, tracepreserving maps. When combined with gradient descent of a cost function, the procedure results in an algorithm for quantum process tomography: finding the quantum process that best fits a set of sufficient observations. We compare the performance of our algorithm to the diluted iterative algorithm as well as second-order solvers interfaced with the popular cvx package for matlab, and find it to be significantly faster and more accurate while guaranteeing a physical estimate.

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Quantum process tomography by 2D fluorescence spectroscopy

Cited by 21 publications

References 46 publications

Implementation of Multivariable Logic Functions in Parallel by Electrically Addressing a Molecule of Three Dopants in Silicon

Implementation of Multivariable Logic Functions in Parallel by Electrically Addressing a Molecule of Three Dopants in Silicon

Towards a spectroscopic protocol for unambiguous detection of quantum coherence in excitonic energy transport

Quantum process tomography via completely positive and trace-preserving projection

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