Quantum

Magic Is in the Eye of the Measure

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Based on a feed excerpt; full article content has not been acquired. Source evidence retrieved 09/11/2026, 05:13:24 UTC.

Briefings

A 2026 study on quantum magic reveals that the optimal measure for calculating non-stabilizerness varies by optimization method, affecting results in nuclear physics. For two qubits, the max-relative entropy and logarithmic free robustness yield a consistent value of sin²θ_W = 1/4, while the min-relative entropy produces an energy-dependent result. This discrepancy highlights that physical conclusions from extremizing magic depend on the specific measure chosen.

Key points

• The max-relative entropy and logarithmic free robustness measures yield a consistent value of sin²θ_W = 1/4 across all energies in Møller scattering for two qubits.
• The min-relative entropy measure produces an energy-dependent value for the weak mixing angle that differs from the SRE result.

Context

Quantum magic is the resource enabling universal quantum computation, with applications in high-energy and nuclear physics relying on stabilizer R'enyi entropy (SRE). This study compares SRE with three optimization-based measures to determine maximal-magic states and find that results depend on the chosen measure.

Limitations

The study covers only two qubits and uses exact proofs for maximal-magic states. Results for higher qubit systems remain unverified, and the energy-dependent discrepancy in the min-relative entropy suggests potential issues with optimization-based measures in broader contexts.

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