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Direct fidelity estimation from few Pauli measurements
1Institute for Quantum Information, California Institute of Technology, Pasadena, California, USA.
Physical Review Letters
|July 21, 2011
Summary
We present a fast, simple method to verify quantum states in experiments. This technique estimates state fidelity using fewer measurements than traditional quantum tomography, improving efficiency for quantum information processing.
Area of Science:
- Quantum Information Science
- Experimental Quantum Physics
Background:
- Accurate preparation and verification of quantum states are crucial for advancing quantum technologies.
- Full quantum state tomography, while comprehensive, is resource-intensive and scales poorly with system size.
Purpose of the Study:
- To develop a more efficient method for certifying the preparation of a desired quantum state in experimental settings.
- To provide an estimate of the fidelity between the prepared and target quantum states.
Main Methods:
- The proposed method involves measuring a constant number of Pauli expectation values.
- Measurements are selected randomly using an importance-weighting strategy.
- The technique is applicable to any pure quantum state.
Main Results:
- The method provides an estimate of the fidelity with a constant additive error.
- It achieves a speedup by a factor of d (the dimension of the state space) compared to full tomography.
- The approach is readily extendable to the characterization of quantum channels.
Conclusions:
- This work introduces a practical and efficient approach for quantum state certification.
- The method reduces the experimental overhead for verifying quantum preparations.
- The technique offers a scalable alternative for assessing quantum state fidelity and has implications for quantum channel characterization.
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