Leakage Error Suppression in Hyperfine Qubits
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Solution Overview
Problem
Trapped atomic object quantum computers, particularly those using hyperfine qubits, face significant leakage errors due to atomic objects transitioning out of defined two-state qubit spaces, leading to errors in quantum computations.
Innovation Solution
A leakage suppression/transformation operation is performed using a controller to apply specific manipulation signals to atomic objects, exciting leaked objects to an intermediary manifold and then to a decay manifold, with the first manipulation signal tuned to suppress excitation of objects within the qubit space and the second signal to facilitate decay back to the ground state, utilizing hyperbolic secant-shaped pulses and carefully controlled wave vectors and polarizations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If atomic objects are used as qubits in trapped atomic object quantum computers, then quantum computations can be performed, but leakage errors occur when atomic objects transition out of the defined two-state qubit space
Solution Approach 1:
The patent introduces an intermediary manifold as a intermediate state between the qubit space and the decay manifold. The first manipulation signal excites leaked atomic objects to this intermediary manifold, which then serves as a transition state before returning to the qubit space. This intermediary structure prevents direct harmful transitions and enables controlled error correction.
Solution Approach 2:
The patent extracts leaked atomic objects from the qubit space by applying the first manipulation signal that selectively targets and excites only those objects that have leaked out. This separation allows the system to identify and correct leakage errors without affecting the properly contained qubits.
2Reliability
If manipulation signals are applied to correct leakage errors, then leakage errors are reduced, but the operation time increases
Solution Approach 1:
The patent employs periodic manipulation signals applied in cycles. The first and second manipulation signals are applied sequentially multiple times to progressively reduce leakage errors. This periodic approach allows the system to maintain qubit integrity while systematically correcting leakage errors over time, balancing reliability improvement with time efficiency.
3Reliability
If the first manipulation signal is tuned to excite leaked atomic objects, then leakage errors can be corrected, but excitation of atomic objects within the qubit space may occur
Solution Approach 1:
The patent applies local quality by tuning the first manipulation signal to have specific frequency and spatial characteristics that make it selectively interact only with leaked atomic objects. The signal's properties are locally optimized to match the energy transition of leaked objects while being off-resonance with qubit objects, enabling selective correction without false excitation.
Solution Approach 2:
The patent utilizes parameter changes in the manipulation signals, specifically adjusting frequency, amplitude, and temporal duration. The first manipulation signal is parameterized to resonate with leaked objects' transition frequencies while suppressing coupling to qubit objects. These parameter optimizations enable selective addressing of leakage errors.
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
This approach effectively reduces leakage errors by several orders of magnitude, improving the fidelity of quantum computations and enabling more effective quantum error correction by returning leaked objects to the qubit space, as demonstrated by simulation results showing a reduction in final leakage error from 10^-4 to 10^-7 within a total operation time of approximately 25µs.
Implementation Method 1
The first manipulation signal is tuned to excite atomic objects within the particular region of the apparatus that have leaked out of a qubit space from a leaked state to an intermediary manifold
Implementation Method 2
The second manipulation signal is tuned to excite atomic objects from the intermediary manifold to a decay manifold
Implementation Method 3
the decay time is determined based on the average time for an atomic object to decay from the decay manifold to a ground state manifold
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A quantum computer comprises an apparatus having atomic objects therein; a first manipulation source configured to provide a first manipulation signal; a second manipulation source configured to provide a second manipulation signal; and a controller. The controller is configured to cause the first manipulation source to provide the first manipulation signal to a region of the apparatus; and cause the second manipulation source to provide the second manipulation signal to the region. The first manipulation signal is tuned to excite atomic objects within the region from a leaked state outside of the qubit space to an intermediary manifold and to suppress excitation of atomic objects that are in the qubit space. The second manipulation signal is tuned to excite atomic objects from the intermediary manifold to a decay manifold from which there is a non-zero probability that an atomic object will decay into the qubit space.