Auxiliary Qubit Reset Echo for Storage Mode Dephasing Control
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Solution Overview
Problem
The f0g1 reset protocol in superconducting circuits causes dephasing errors in storage modes due to the rotation of qubit states during the reset process, which is inefficient for high-performance quantum computing.
Innovation Solution
A 'Reset Echo' protocol involving two ηge pulses separated by an echo time duration, followed by ηef and f0g1 pulses, aligns the |f state with the |g state to minimize dephasing errors, using an effective Hamiltonian Hecho,eff=2χa†a|gg|.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the f0g1 reset protocol is used to reset the auxiliary qubit, then the reset speed is improved, but dephasing errors in the storage mode increase
Solution Approach 1:
The patent applies preliminary anti-action by implementing an echo pulse sequence before the reset operation. The first ηge pulse rotates the qubit state, followed by an echo time period where the state evolves under the effective Hamiltonian Hecho,eff=2χa†a|gg|, and then a second ηge pulse completes the rotation. This preliminary rotation sequence counteracts the dephasing that would otherwise occur during the subsequent f0g1 reset, thereby preserving storage mode fidelity while maintaining fast reset speeds.
Solution Approach 2:
The patent implements preliminary action by preparing the auxiliary qubit in a specific rotational state through the ηge pulse sequence before executing the reset. By pre-rotating the qubit state to align with the effective Hamiltonian evolution during the echo time, the system ensures that the subsequent reset operation does not induce dephasing errors in the storage mode, thus preparing the system in advance to avoid the harmful effect.
2Reliability
If natural relaxation is used to reset the qubit, then dephasing errors are minimized, but the reset time becomes unacceptably long
Solution Approach 1:
The patent introduces an intermediary mechanism - the echo pulse sequence with effective Hamiltonian Hecho,eff=2χa†a|gg| - that mediates between the conflicting requirements of fast reset and low dephasing. This intermediary rotation protocol allows the system to achieve rapid state preparation without directly invoking the dissipative relaxation process, thereby decoupling the reset speed from the dephasing error rate that would otherwise be coupled in natural relaxation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The protocol significantly reduces dephasing errors by realigning qubit states, improving quantum computing performance by up to 40% with a 5 us inter-round delay.
Implementation Method 1
performing on the auxiliary qubit a first ηge pulse causing a |g↔|e transition in said auxiliary qubit
Implementation Method 2
The easiest method to achieve such a reset in superconducting circuits is to use the natural relaxation of the circuit to its ground state
Implementation Method 3
driving, via a second microwave drive, a |f0↔|g1 transition in said auxiliary qubit
Data Source
AI summary
Described are various embodiments of a system and method for minimizing a storage mode dephasing error caused by a reset of the auxiliary qubit. In one embodiment, the method comprises the steps of performing on the auxiliary qubit a first ηge pulse causing a |g↔|e transition in said auxiliary qubit, waiting for a designated echo time duration; and performing on the auxiliary qubit a second ηge pulse. The method may further comprise performing a f0g1 reset on the auxiliary qubit.