This talk will represent the official presentation to GIQ of the newly established Quantum Computation Technology (QCT) group at IFAE. I will introduce the group and its primary focus to build a quantum annealer using superconducting qubit technology to run quantum algorithms and perform computation and simulation tasks. Quantum annealing has kept raising interests since its inception. The lack of experimental implementations has limited its exploitation.
In this informal talk, I will show that the weak equivalence principle (WEP) is violated for a quantum particle in a gravitational wave (GW) background. In a freely-falling frame, the expected trajectory of a quantum particle is independent of the GW, but its probability distribution is not. By monitoring the position of the particle, extra mass information can be extracted due to the GW, in violation of the WEP.
Given a general d-dimensional unitary operation for which, apart from the dimension, its description is unknown, is it possible to implement its inverse operation with a universal protocol that works for every unitary? How does the situation change when k uses of unitary operation are allowed? In this paper we show that any universal protocol implementing the inverse of a general unitary with a positive heralded probability requires at least d−1 uses of this unitary.
I will present new results on the problem of estimating the overlap of two arbitrary quantum states in any finite dimension, given any number of copies of each of them. This problem is of wide interest for applications in quantum technologies and our study provides a full characterization of the optimal strategy, as well as several natural (sub-optimal) strategies including the widely used swap-test. I will also review a powerful graphical method based on the recoupling theory of SU(2), which proved very useful for our study.
The issue of optimally estimating parameters associated with quantum channels has been thoroughly studied in various contexts, yielded an enhancement of accuracy using resources such as entangled states. For various qubit channels, using the quantum Fisher information per channel invocation as a measure of the estimation accuracy, optimal estimation protocols and the possible advantages that they might yield are well understood. However, these resulting optimal estimation protocols usually require pure initial states.
A number of noncontextual models exist which reproduce different subsets of quantum theory and admit a no-cloning theorem. Therefore, if one chooses noncontextuality as one's notion of classicality, no-cloning cannot be regarded as a nonclassical phenomenon. However, in the work that I'll present in this talk, we show that the phenomenology of quantum state cloning is indeed nonclassical, but not for the reasons usually given.
One of the fundamental concepts in statistical mechanics is the notion of ergodicity, which is closely related to the lack of memory of a system. In quantum mechanics, it is observed that the interactions redistribute the available
Blockchain technologies are beginning to mature and are triggering great interest both in academic and industrial fields. At the technical level, the Blockchain
incorporates concepts from different areas of knowledge such as computer networks, distributed systems, consensus algorithms, security and cryptography,
programming and game theory to create a state machine equally shared among many entities. In this talk I will start by describing a classical centralized