About QUINST

Quantum mechanics is at the heart of our technology and economy - the laser and the transistor are quantum devices - but its full potential is far from being realized. Recent technological advances in optics, nanoscience and engineering allow experimentalists to create artificial structures or put microscopic and mesoscopic systems under new manipulable conditions in which quantum phenomena play a fundamental role.

Quantum technologies exploit these effects with practical purposes. The objective of Quantum Science is to discover, study, and control quantum efects at a fundamental level. These are two sides of a virtuous circle: new technologies lead to the discovery and study of new phenomena that will lead to new technologies.

Our aim is  to control and understand quantum phenomena in a multidisciplinary intersection of  Quantum Information, Quantum optics and cold atoms, Quantum Control, Spintronics, Quantum metrology, Atom interferometry, Superconducting qubits and Circuit QED and Foundations of Quantum Mechanics.

QUINST is funded in part as a “Grupo Consolidado” from the Basque Government (IT472-10, IT986-16, IT1470-22)  and functions as a network of groups with their own funding, structure, and specific goals.  

Latest events

Seminar

Hefeng Wang,  (Advanced Science Institute, The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama, Japan)

When and where

From: 11/2010 To: 11/2016

Description

2009/10/08, Hefeng Wang,  (Advanced Science Institute, The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama, Japan)

Place: Sala de Seminarios del Departamento de Física Teórica e Historia de la Ciencia
Time: 12h.
Title: Efficient quantum algorithm for preparing molecular-system-like states on a quantum computer


Abstract
 We present an efficient quantum algorithm for preparing a pure state on a quantum computer, where the quantum state corresponds to that of a molecular system with a given number $m$ of electrons occupying a given number $n$ of spin orbitals. Each spin orbital is mapped to a qubit: the states $\vert 1 \rangle$ and $\vert 0 \rangle$ of the qubit represent, respectively, whether
 the spin orbital is occupied by an electron or not. To prepare a general state in the full Hilbert space of $n$ qubits, which is of dimension $2^{n}$% , $O(2^{n})$ CNOT gates are needed, i.e.~the number of gates scales \emph{% exponentially} with the number of qubits. We make use of the fact that the state to be prepared lies in a smaller Hilbert space, and we find an algorithm that requires at most $O(2^{m+1} n^{m}/{m!})$ gates, i.e.~scales \emph{polynomially} with the number of qubits $n$, provided $n\gg m$. The algorithm is simulated numerically for the cases of the hydrogen molecule and the water molecule. The numerical simulations show that when additional symmetries of the system are considered, the number of gates to prepare the state can be drastically reduced; in the examples considered in this paper,
 by several orders of magnitude, from the above estimate.
 (Phys. Rev. A, 79, 042335, 2009)