In this paper, we design and experimentally implement various robust quantum unitary transformations (gates) acting on d -dimensional vectors (qudits) by tuning a single control parameter using optimal control theory. The quantum state is represented by the momentum components of a Bose-Einstein condensate placed in an optical lattice, with the lattice position varying over a fixed duration serving as the control parameter. To evaluate the quality of these transformations, we employ standard quantum process tomography. In addition, we show how controlled unitary transformations can be used to extend state stabilization to global stabilization within a controlled vector subspace. Finally, we apply them to state tomography, showing how the information about the relative phase between distant momentum components can be extracted by inducing an interference process.In this paper, we design and experimentally implement various robust quantum unitary transformations (gates) acting on d -dimensional vectors (qudits) by tuning a single control parameter using optimal control theory. The quantum state is represented by the momentum components of a Bose-Einstein condensate placed in an optical lattice, with the lattice position varying over a fixed duration serving as the control parameter. To evaluate the quality of these transformations, we employ standard quantum process tomography. In addition, we show how controlled unitary transformations can be used to extend state stabilization to global stabilization within a controlled vector subspace. Finally, we apply them to state tomography, showing how the information about the relative phase between distant momentum components can be extracted by inducing an interference process.

arXiv:2503.08230Physical Review ResearchMay 12, 20252 citations

Quantum State Tomography of Spin Qubits

Oliver Dial

Bulletin of the American Physical SocietyMar 19, 20130 citations

Enhanced compressive threshold quantum state tomography for qudit systems

Giovanni Garberoglio, Maurizio Dapor, Diego Maragnano +2 more

We propose an efficient quantum state tomography method inspired by compressed sensing and threshold quantum state tomography that can drastically reduce the number of measurement settings to reconstruct the density matrix of an $N$ -qudit system. We validate our algorithm with demonstrations on IBMQ and show the efficient and accurate reconstruction of $N\ensuremath{\le}7$ qubit systems, reproducing GHZ, $\mathrm{W}$ , and random states with $O(1)$ , $O({N}^{2})$ , and $O(N)$ settings.We propose an efficient quantum state tomography method inspired by compressed sensing and threshold quantum state tomography that can drastically reduce the number of measurement settings to reconstruct the density matrix of an $N$-qudit system. We validate our algorithm with demonstrations on IBMQ and show the efficient and accurate reconstruction of $N\ensuremath{\le}7$ qubit systems, reproducing GHZ, $\mathrm{W}$, and random states with $O(1)$, $O({N}^{2})$, and $O(N)$ settings.

arXiv:2502.10031Physical Review AMar 28, 20251 citation

N

-qudit system. We validate our algorithm with demonstrations on IBMQ and show the efficient and accurate reconstruction of $N\ensuremath{\le}7$ qubit systems, reproducing GHZ,

\mathrm{W}

, and random states with

O(1)

O({N}^{2})

, and

O(N)

settings.