Quantum Bus Device for Coherent Qubit Transfer

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Solution Overview

Problem

Topological quantum computing systems face challenges in coherently transferring quantum information due to the non-local nature of their degrees of freedom, making it difficult to couple with external systems in a controlled and coherent manner, especially when trying to create quantum entanglement between topological and conventional states.

Innovation Solution

A quantum bus device is implemented using Majorana wire networks and semiconductor nanowires with s-wave superconductors, employing the Aharonov-Casher effect for joint parity measurements to entangle and coherently transfer quantum information between topological and conventional qubits, allowing for error correction and universal gate operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If topological quantum computing systems use non-local degrees of freedom for fault tolerance, then error rates are exponentially suppressed, but coupling with external systems becomes difficult and coherent information transfer is challenging

Engineering Contradiction:

Improveerror rate suppressionVSAvoidcoupling with external systems

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent introduces an intermediary mechanism (quantum bus involving Majorana modes and conventional qubits) that mediates between the topologically protected non-local degrees of freedom and external conventional quantum systems. This intermediary enables controlled coupling and coherent information transfer while preserving the error suppression benefits of topological protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If topologically protected braiding operations are used alone for Ising anyons, then fault tolerance is improved, but a computationally universal gate set cannot be produced

Engineering Contradiction:

Improvefault toleranceVSAvoidcomputationally universal gate set

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent merges topologically protected braiding operations with topologically unprotected conventional quantum gate operations. By combining these two types of operations through the quantum bus interface, the system achieves both fault tolerance from topological protection and computational universality from conventional gates, enabling a complete quantum computing system.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If quantum entanglement is created between topological and conventional states, then coherent information transfer is enabled, but coupling control becomes more challenging

Engineering Contradiction:

Improvecoherent information transferVSAvoidcoupling control

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent segments the quantum system into distinct topological and conventional domains connected by a controlled interface (quantum bus). This segmentation allows each domain to operate with its own optimized control mechanisms while the interface provides structured coupling, making the overall system more manageable despite the complexity of creating entanglement between different types of quantum states.

Inventive Principle:

Principle #1Segmentation

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

Enables efficient error correction and universal gate operations by importing topologically unprotected gates from conventional systems, achieving error rates below 0.14% and facilitating quantum information transfer between various qubit pairs, including topological-topological and conventional-conventional pairs.

Implementation Method 1

employing the Aharonov-Casher effect for joint parity measurements to entangle and coherently transfer quantum information between topological and conventional qubits

Methodology Applied

Scientific EffectAharonov-Casher effect:

Data Source

PatentUS9152924B2Coherent quantum information transfer between conventional qubits

Publication Date: 2015.10.06 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

Computing bus devices that enable quantum information to be coherently transferred between conventional qubit pairs are disclosed. A concrete realization of such a quantum bus acting between conventional semiconductor double quantum dot qubits is described. The disclosed device measures the joint (fermion) parity of the two qubits by using the Aharonov-Casher effect in conjunction with an ancillary superconducting flux qubit that facilitates the measurement. Such a parity measurement, together with the ability to apply Hadamard gates to the two qubits, allows for the production of states in which the qubits are maximally entangled, and for teleporting quantum states between the quantum systems.