Quantum-state tomography for spin-l systems (8 pages)

Augusto J. Roncaglia, Juan Pablo Paz

Oliver Dial

Gustavo Rigolin

We show that the teleportation-based quantum state tomography (QST) protocol, originally built to reconstruct qubits (spin-1/2 systems), can be extended to deal with qutrits (spin-1 systems) as well. Similarly to the original proposal, only two resources are needed to implement the spin-1 teleportation-based QST protocol: (1) Alice should be able to implement the analog of Bell measurements for spin-1 systems; and (2) she should be able to prepare a few different single qutrit states that will be teleported to Bob.

Jaroslav Řeháček, Berthold‐Georg Englert, Dagomir Kaszlikowski

Jae‐Seung Lee

J. Teles, Eduardo Ribeiro DeAzevedo, R. Auccaise +3 more

In this paper, we describe a quantum state tomography method based on global rotations of the spin system which, together with a coherence selection scheme, enables the complete density matrix reconstruction. The main advantage of this technique, in respect to previous proposals, is the use of much shorter rf pulses, which decreases significantly the time necessary for algorithm quantum state tomography. In this case, under adequate experimental conditions, the rf pulses correspond to simple spatial rotations of the spin states, and its analytical description is conveniently given in the irreducible tensor formalism. Simulated results show the feasibility of the method for a single spin 72 nucleus. As an experimental result, we exemplify the application of this method by tomographing the steps during the implementation of the Deutsch algorithm. The algorithm was implemented in a (23)Na quadrupole nucleus using the strongly modulated pulses technique. We also extended the tomography method for a 3-coupled homonuclear spin 12 system, where an additional evolution under the internal Hamiltonian is necessary for zero order coherences evaluation.