Quantum tomography of three-qubit state

Naser Karimi, Marziyeh Yahyavi

Kenta Takeda, Akito Noiri, Takashi Nakajima +3 more

Artur Czerwiński

In this paper, we introduce a numerical framework for quantum tomography and entanglement quantification of three-qubit generalized Werner states. The scheme involves the single-qubit symmetric, informationally complete, positive operator-valued measure (SIC-POVM), which is then generalized to perform three-qubit measurements. We introduce random errors into the scheme by imposing the Poisson noise on the measured photon counts. The precision of state estimation is quantified and presented on graphs. As a special case, we compare the efficiency of the framework for the pure three-qubit generalized Werner state and the W state. The reconstructed states are presented graphically and discussed.

Joseph B. Altepeter, Daniel F. V. James, Paul G. Kwiat

Humera Talath, Govindaraja B.P., Divyamani B.G. +3 more

Abstract We present a three-qubit quantum state tomography scheme requiring a set of 17 measurements, significantly reducing the experimental overhead compared to the conventional 63 Pauli measurements. Using IBM's 127-qubit open-access quantum processor \texttt{ibm\textunderscore{osaka}}, we prepare the three-qubit W state and employ our tomography scheme to reconstruct it. Additionally, we implement a two-qubit tomography protocol, involving a set of 7 measurements, on \texttt{ibm\textunderscore{osaka}} to reconstruct {\em two} of the two-qubit marginals of the W state. This serves as a {\em proof-of-principle} demonstration of the well-known theoretical result that any two of the two-qubit reduced density matrices can uniquely determine most of the whole three-qubit pure states. We show that the fidelity of the W-state reconstructed from its two-qubit subsystems is consistently larger than that obtained from the full three-qubit tomography, highlighting the practical advantage of the subsystem-based tomography approach.

Oliver Dial