Programmable Qubit Connectivity for Quantum Processor Topology
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Solution Overview
Problem
Current quantum processors face limitations in the number and complexity of problems they can solve due to constraints in qubit connectivity and interaction, which restricts the size and complexity of optimization problems that can be embedded within the processor architecture.
Innovation Solution
The introduction of programmable or logically defined connectivities allows for an arbitrary number of possible connections between qubits, enabling the creation of different processor graphs that support various connectivity configurations, including complete graphs and specific topologies like K5 and K3,3, which can be set during calibration or configuration stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If qubit connectivity is constrained by fixed processor architecture, then device complexity is reduced, but the number and complexity of solvable problems is limited
Solution Approach 1:
The patent implements dynamically reconfigurable qubit connectivity through programmable couplers that can establish different coupling configurations between qubits based on the specific problem being solved. This allows the processor architecture to adapt its connectivity pattern dynamically, enabling solving of diverse optimization problems with varying graph topologies without permanently increasing physical hardware complexity.
Solution Approach 2:
The patent creates a universal quantum processor platform where a single set of qubits and couplers can serve multiple problem types by reconfiguring connectivity patterns. The same physical hardware can embed different problem graphs (e.g., complete graphs, bipartite graphs, or arbitrary topologies) by programming different coupling configurations, making the processor universally applicable to various optimization problems.
2Quantity of substance
If the number of qubit connections is increased to solve larger optimization problems, then problem complexity capacity increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of manufacturing processors with fixed high-connectivity architectures, the patent uses programmable couplers that can dynamically establish multiple connection patterns between the same physical qubits. This allows the system to achieve high effective connectivity (solving large problems) without requiring correspondingly high physical connectivity during manufacturing, greatly simplifying fabrication.
Solution Approach 2:
The patent uses virtual or logical representations of problem graphs that are mapped onto the physical qubit array through software control. Rather than physically constructing every possible qubit connection, the system creates virtual connection patterns through programming, allowing arbitrary graph topologies to be embedded without proportional increases in physical hardware complexity.
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 enhances the ability of quantum processors to solve a wider range of problems by increasing the number of possible connections between qubits, thereby expanding the complexity and size of optimization problems that can be addressed.
Implementation Method 1
a coupler including: a first coupling portion; a second coupling portion... to effect a magnetic coupling between the first superconducting flux qubit and the coupler, a fourth switch in parallel with the second coupling portion of the coupler, and the second coupling portion of the coupler is arranged with respect to the second superconducting flux qubit to effect a magnetic coupling between the second superconducting flux qubit and the coupler
Implementation Method 2
superconducting circuits. Both spin and superconductivity are quantum mechanical phenomena
Data Source
AI summary
In a quantum processor some couplers couple a given qubit to a nearest neighbor qubit (e.g., vertically and horizontally in an ordered 2D array), other couplers couple to next-nearest neighbor qubits (e.g., diagonally in the ordered 2D array). Couplers may include half-couplers, to selectively provide communicative coupling between a given qubit and other qubits, which may or may not be nearest or even next-nearest-neighbors. Tunable couplers selective mediate communicative coupling. A control system may impose a connectivity on a quantum processor, different than an “as designed” or “as manufactured” physical connectivity. Imposition may be via a digital processor processing a working or updated working graph, to map or embed a problem graph. A set of exclude qubits may be created from a comparison of hardware and working graphs. An annealing schedule may adjust a respective normalized inductance of one or more qubits, for instance to exclude certain qubits.