1. B O S C H U N D S I E M E N S H A U S G E R Ä T E G R U P P E Utilizing error correction for quantum sensing Yuval Vinkler Hebrew University of Jerusalem Work done with: Alex Retzker Gilad Arrad Dorit Aharonov Talk at the Israel Physical Society Conference 1.12.2013

2. Quantum Sensing Quantum sensing scales as: One method to improve coherence time: dynamical decoupling. In Quantum sensing a signal is measured by reading its effects on a system. For example: for a signal g along the z direction Can this be done with error correction?

3. General Idea of error correction for quantum computing Code error1 error2 Error N Logical operation

4. General Idea of error correction for quantum sensing Code error1 error2 Error N Sensing signal However, the sensing signal is weak/slow and the logical operation is strong/fast

5. Advantage – use of protected qubits Code Sensing qubit Good qubits

6. Magnetic noise The code using a good qubit: noise signal The effect of noise: Signal: While dynamical decoupling must operate faster than the correlation time of the noise, error correction must work faster than the magnitude of the noise, regardless its power spectrum.

7. Magnetic Noise – Numerical Simulation Works even with strong noise (with respect to g). Strong dependence on the frequency of operations – the faster we act, the better the signal.

8. Summary The principles of Error Corrections were employed to improve quantum sensing. For noise perpendicular to the sensing signal – a significant improvement in coherence time. Operations must be faster than noise strength. Can be slower noise power spectrum. Outlook: experiments (in progress), decoherence type spectroscopy. The principles of Error Corrections were employed to improve quantum sensing. For noise perpendicular to the sensing signal – a significant improvement in coherence time. Operations must be faster than noise strength. Can be slower noise power spectrum. Outlook: experiments (in progress), decoherence type spectroscopy.