Filtering Crosstalk from Bath Non-Markovianity via Spacetime Classical Shadows

Area of Science:

• Quantum Information Science
• Quantum Dynamics
• Quantum Correlations

Background:

• Non-Markovian effects in open quantum systems can arise from external baths or neighboring quantum bits (qubits).
• Distinguishing between these sources is crucial, especially when neighboring qubits are controllable, unlike inaccessible baths.
• Characterizing spatiotemporal quantum correlations is essential for understanding complex quantum systems.

Purpose of the Study:

• To develop a method for distinguishing quantum correlations caused by controllable neighboring qubits from those caused by inaccessible environments.
• To provide a technique for filtering out crosstalk and isolating non-Markovian effects from external baths.
• To enable the study of spatiotemporally spreading correlated noise in quantum systems.

Main Methods:

• Combining non-Markovian quantum process tomography with the classical shadows framework.
• Utilizing a maximally depolarizing channel as a 'causal break' to systematically erase temporal correlations.
• Employing observables as operations applied to the system to probe quantum correlations.

Main Results:

• Demonstrated a procedure to effectively filter out crosstalk, isolating non-Markovianity from inaccessible baths.
• Provided a method to analyze spatiotemporally spreading correlated noise originating from common environments across a quantum lattice.
• Showcased the efficiency of the method on synthetic data, highlighting its scalability.

Conclusions:

• The developed procedure efficiently distinguishes between different sources of non-Markovian dynamics in open quantum systems.
• Classical shadows enable the arbitrary removal of neighboring qubits' influence at no additional computational cost.
• This technique is highly scalable and applicable to quantum systems with complex interaction topologies, including all-to-all interactions.