Luciano Iván Pereira

Luciano Iván Pereira
Spanish National Research Council | CSIC · Institute of Fundamental Physics

Master of Physics

About

25
Publications
1,602
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103
Citations
Citations since 2017
25 Research Items
103 Citations
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Introduction
I research on characterization method of quantum hardware.
Education
March 2016 - May 2018
University of Concepción
Field of study
  • Quantum Tomography

Publications

Publications (25)
Preprint
Full-text available
Entangled states play a fundamental role in Quantum Mechanics and are at the core of many contemporary applications, such as quantum communication and quantum computing. Therefore, determining whether a state is entangled or not is an important task. Here, we propose a method to detect the entanglement of unknown two-qubit quantum states. Our metho...
Article
Full-text available
The most common form of measurement in quantum mechanics projects a wavefunction onto orthogonal states that correspond to definite outcomes. However, generalized quantum measurements that do not fully project quantum states are possible and have an important role in quantum information tasks. Unfortunately, it is difficult to certify that an exper...
Article
Full-text available
We introduce an inductive n -qubit pure-state estimation method based on projective measurements on m n + 1 separable bases or m entangled bases plus the computational basis, with m ≥ 2. The method exhibits a favorable scaling in the number of qubits compared to other estimation schemes. The use of separable bases makes our estimation method partic...
Article
Current noise levels in physical realizations of qubits and quantum operations limit the applicability of conventional methods to characterize entanglement. In this adverse scenario, we follow a quantum variational approach to estimate the geometric measure of entanglement of multiqubit pure states. The algorithm requires only single-qubit gates an...
Article
We introduce a self-consistent tomography for arbitrary quantum nondemolition (QND) detectors. Based on this, we build a complete physical characterization of the detector, including the measurement processes and a quantification of the fidelity, ideality, and backaction of the measurement. This framework is a diagnostic tool for the dynamics of QN...
Preprint
Full-text available
An efficient characterization of QND measurements is an important ingredient towards certifying and improving the performance and scalability of quantum processors. In this work, we introduce a protocol for the parallelized QND measurement tomography (QND-MT) of a multiqubit quantum processor that addresses single- and two-qubit measurements. We de...
Preprint
Full-text available
Hybrid classical quantum optimization methods have become an important tool for efficiently solving problems in the current generation of NISQ computers. These methods use an optimization algorithm that is executed in a classical computer, which is fed with values of the objective function that are obtained in a quantum computer. Therefore, a prope...
Preprint
Full-text available
We present a complex field formulation of the quantum Fisher estimation theory that works natively with complex statistics on the dependence of complex parameters. This states new complex versions of the main quantities and results of the estimation theory depending on complex parameters, such as Fisher information matrices and Cram\'er-Rao bounds....
Preprint
Full-text available
Variational algorithms have received significant attention in recent years due to their potential to solve practical problems in noisy intermediate-scale quantum (NISQ) devices. A fundamental step of these algorithms is the evaluation of the expected value of Hamiltonians. Efficient schemes to perform this task are required to speed up these algori...
Preprint
Full-text available
Generalised quantum measurements go beyond the textbook concept of a projection onto an orthonormal basis in Hilbert space. They are not only of fundamental relevance but have also an important role in quantum information tasks. However, it is highly demanding to certify that a generalised measurement is indeed required to explain the results of a...
Preprint
Full-text available
Here, we study the problem of decoding information transmitted through unknown quantum states. We assume that Alice encodes an alphabet into a set of orthogonal quantum states, which are then transmitted to Bob. However, the quantum channel that mediates the transmission maps the orthogonal states into non-orthogonal states, possibly mixed. If an a...
Preprint
Full-text available
Current noise levels in physical realizations of qubits and quantum operations limit the applicability of conventional methods to characterize entanglement. In this adverse scenario, we propose a variational algorithm to estimate the geometric measure of entanglement of multiqubit pure states. The algorithm requires only single-qubit gates and meas...
Preprint
Full-text available
We introduce a self-consistent tomography for arbitrary quantum non-demolition (QND) detectors. Based on this, we build a complete physical characterization of the detector, including the measurement processes and a quantification of the fidelity, ideality, and back-action of the measurement. This framework is a diagnosis tool for the dynamics of Q...
Preprint
Full-text available
We introduce an inductive $n$-qubit pure-state estimation method. This is based on projective measurements on states of $2n+1$ separable bases or $2$ entangled bases plus the computational basis. Thus, the total number of measurement bases scales as $O(n)$ and $O(1)$, respectively. Thereby, the proposed method exhibits a very favorable scaling in t...
Article
We introduce a method to estimate unknown pure d-dimensional quantum states using the probability distributions associated with only three measurement bases. The measurement results of 2d projectors are used to generate a set of 2d−1 states, the value of the likelihood function of which is evaluated using the measurement results of the remaining d...
Preprint
Full-text available
The accuracy of estimating $d$-dimensional quantum states is limited by the Gill-Massar bound. It can be saturated in the qubit ($d=2$) scenario using adaptive standard quantum tomography. In higher dimensions, however, this is not the case and the accuracy achievable with adaptive quantum tomography quickly deteriorates with increasing $d$. Moreov...
Preprint
Full-text available
In this article we propose a method to estimate with high accuracy pure quantum states of a single qudit. Our method is based on the minimization of the squared error between the complex probability amplitudes of the unknown state and its estimate. We show by means of numerical experiments that the estimation accuracy of the present method, which i...
Article
Full-text available
Quantum tomography has become a key tool for the assessment of quantum states, processes, and devices. This drives the search for tomographic methods that achieve greater accuracy. In the case of mixed states of a single 2-dimensional quantum system adaptive methods have been recently introduced that achieve the theoretical accuracy limit deduced b...
Preprint
Full-text available
Quantum tomography has become a key tool for the assessment of quantum states, processes, and devices. This drives the search for tomographic methods that achieve greater accuracy. In the case of mixed states of a single 2-dimensional quantum system adaptive methods have been recently introduced that achieve the theoretical accuracy limit deduced b...
Preprint
Full-text available
We introduce a new method to estimate unknown pure $d$-dimensional quantum states using the probability distributions associated with only three measurement bases. Measurement results of $2d$ projectors are employed to generate a set of $2^{d-1}$ possible states, the likelihood of which is evaluated using the measurement results of the $d$ remainin...
Article
Multi-port beam splitters are cornerstone devices for high-dimensional quantum information tasks, which can outperform the two-dimensional ones. Nonetheless, the fabrication of such devices has proven to be challenging with progress only recently achieved with the advent of integrated photonics. Here, we report on the production of high-quality N ×...
Preprint
Full-text available
Universal multi-port interferometers that can be reconfigured to implement any unitary operation are crucial for photonic universal quantum computation, optical neural networks, and boson sampling. Recently, Saygin et al. [Phys. Rev. Lett. 124, 010501 (2020)] have presented numerical evidence that an extremely compact arrangement consisting in $d$...
Preprint
Full-text available
Multi-port beamsplitters are cornerstone devices for high-dimensional quantum information tasks, which can outperform the two-dimensional ones. Nonetheless, the fabrication of such devices has been proven to be challenging with progress only recently achieved with the advent of integrated photonics. Here, we report on the production of high-quality...
Article
Full-text available
It has been recently shown that for quantum systems with dimension d≥4 unknown pure states can be estimated via measurements on five bases only. Here, we study by means of numerical experiments the estimation accuracy of this method as a function of the dimension and the number of independently, identically prepared copies, that is, ensemble size....
Article
Full-text available
Standard quantum tomography of a single qudit achieves an infidelity that scales in the worst case as O(1/N) for a sample of size N. Here, we propose a suitable generalization of the two-stage adaptive quantum tomography for a qubit to the case of a single qudit. This achieves an infidelity of the order of O[1/N0(N−N0)] for all quantum states, wher...

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