Efficient quantum state tomography with auxiliary Hilbert space

TL;DR

This paper introduces a new quantum state tomography method using auxiliary Hilbert space, simplifying measurements for high-dimensional quantum states and demonstrated with orbital angular momentum states of photons.

Contribution

The paper presents a novel auxiliary Hilbert space tomography technique that eliminates the need for pre-rotations, simplifying high-dimensional quantum state measurements.

Findings

Achieved over 95% fidelity in reconstructing quantum states up to dimension 13.

Demonstrated the method with orbital angular momentum states of photons.

Simplified measurement process to a camera photograph.

Abstract

Quantum state tomography is an important tool for quantum communication, computation, metrology, and simulation. Efficient quantum state tomography on a high dimensional quantum system is still a challenging problem. Here, we propose a novel quantum state tomography method, auxiliary Hilbert space tomography, to avoid pre-rotations before measurement in a quantum state tomography experiment. Our method requires projective measurements in a higher dimensional space that contains the subspace that includes the prepared states. We experimentally demonstrate this method with orbital angular momentum states of photons. In our experiment, the quantum state tomography measurements are as simple as taking a photograph with a camera. We experimentally verify our method with near-pure- and mixed-states of orbital angular momentum with dimension up to $d=13$, and achieve greater than 95 % state fidelities for all states tested. This method dramatically reduces the complexity of measurements for full quantum state tomography, and shows potential application in various high dimensional quantum information tasks.