Multirail Qubit Encoding with Mode Erasure for Reliable Detection
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Solution Overview
Problem
The practical realization of quantum computers is hindered by the reliable creation and entangling of qubits, which is a challenging task in existing technologies.
Innovation Solution
A system for determining the logical state of a qubit is developed, utilizing a quantum system with a state space partitioned into multiple modes, where occupancy of specific modes is mapped to logical states, and employing detectors and measurement logic to signal the logical zero or one, along with mode-information erasure circuits to preserve total occupancy information while destroying specific occupancy information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple modes are used to encode qubit states, then the reliability of qubit state determination is improved, but the device complexity increases
Solution Approach 1:
The patent divides the quantum state space into multiple discrete modes (e.g., spatial modes in different waveguides) and assigns each mode to represent a specific qubit state. This segmentation allows reliable state determination by detecting which mode is occupied, while managing complexity through structured organization of modes into bands with specific detection protocols.
Solution Approach 2:
The patent introduces mode-information eraser circuits as intermediary components that process the quantum states by erasing unnecessary mode information while preserving the essential qubit state information. These circuits act as mediators between the complex multi-mode quantum system and the simplified detection process, enabling reliable state determination without requiring direct measurement of all mode details.
2Measurement precision
If mode-information is erased to preserve total occupancy, then the measurement precision is improved, but the loss of information increases
Solution Approach 1:
The patent extracts and preserves only the essential information needed for qubit state determination (total occupancy of modes in each band) while discarding unnecessary detailed information about which specific mode is occupied. The mode-information eraser circuits perform this extraction by preserving total occupancy counts while erasing individual mode identification, achieving precise measurement without retaining superfluous information.
Solution Approach 2:
The patent transforms the measurement approach by changing from detecting individual mode occupancy details to measuring total occupancy parameters across mode bands. This parameter transformation allows the system to maintain measurement precision for qubit state determination while accepting the loss of fine-grained mode information, as the preserved parameter (total occupancy) is sufficient for logical state identification.
Data Source
AI summary
A multirail-encoded qubit can be implemented using a quantum system having a state space that includes a number M of distinct modes, where M is an integer greater than 2. The M modes are logically partitioned into two disjoint subsets (or “bands”), with each mode assigned to exactly one of the bands. The multirail encoding is defined such that a state in which any one of the modes in the first band is occupied and all modes in the second band are unoccupied maps to a logical 0 state of the qubit, and a state in which any one of the modes in the second band is occupied and all modes of the first band are unoccupied maps to a logical 1 state. Systems and methods for generating, measuring, and operating on multirail-encoded qubits are disclosed.