Superconducting Qubit Couplers for Universal Adiabatic Computing
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Solution Overview
Problem
Existing approaches to adiabatic quantum computing, such as adiabatic quantum optimization, lack the full functionality of a universal quantum computer and have limitations in practical implementation, particularly in achieving universal quantum computing capabilities.
Innovation Solution
A quantum processor design incorporating a pair of hybrid qubits with in-situ tunable superconducting capacitive and inductive couplers, enabling tunable diagonal and off-diagonal couplings, and a method for reading qubit states through a scalable shift register, allowing for universal adiabatic quantum computing and quantum annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If adiabatic quantum optimization is used, then the system can find ground states of Hamiltonians, but it lacks universal quantum computing functionality
Solution Approach 1:
The patent implements a universal quantum processor that can perform both adiabatic quantum optimization and gate-model quantum computing operations. The system uses a configurable Hamiltonian with tunable coupling elements that can be adjusted to implement different computational models, allowing the same hardware to execute multiple quantum algorithms and simulation tasks beyond just optimization problems.
Solution Approach 2:
The patent employs dynamically tunable coupling elements between qubits that can be adjusted during computation. The coupling strength and sign can be changed in real-time, allowing the system to transition between different computational regimes and implement time-dependent Hamiltonians required for universal quantum computing, rather than being fixed to a single optimization mode.
2Adaptability or versatility
If fixed couplings are used in adiabatic quantum computing, then the processor structure is simpler, but it cannot achieve universal quantum computing capabilities
Solution Approach 1:
The patent implements dynamically controllable coupling elements between qubits whose strength and sign can be tuned during computation. This dynamic coupling allows the system to implement complex Hamiltonians with both diagonal and off-diagonal terms, enabling universal quantum computing while maintaining a relatively simple physical architecture based on superconducting circuits.
Solution Approach 2:
The patent changes the parameters of the coupling elements (strength and sign) during computation to implement different computational models. By dynamically adjusting these parameters, the system can transition between adiabatic optimization and gate-model operations, achieving computational universality without requiring fundamentally different hardware for each mode.
3Adaptability or versatility
If diagonal coupling only is implemented, then the processor is easier to control, but it cannot simulate general quantum computers
Solution Approach 1:
The patent implements both diagonal and off-diagonal coupling elements in the quantum processor. The diagonal couplings (σz⊗σz terms) provide controllable interactions between qubits, while the off-diagonal couplings (σx⊗σx and σy⊗σy terms) enable quantum tunneling and transitions between computational basis states. This combination allows the system to simulate general quantum computers and implement a universal set of quantum gates.
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 the realization of a universal adiabatic quantum computer capable of simulating any quantum computer, overcoming previous limitations in adiabatic quantum computing by providing tunable couplings and efficient state reading mechanisms.
Implementation Method 1
a first in-situ tunable superconducting capacitive coupler having a tunable capacitance
Implementation Method 2
a first in-situ tunable superconducting inductive coupler having a tunable inductance
Implementation Method 3
Each of the qubits of the first pair of qubits may be a respective hybrid qubit
Data Source
AI summary
A quantum processor is operable as a universal adiabatic quantum computing system. The quantum processor includes physical qubits, with at least a first and second communicative coupling available between pairs of qubits via an in-situ tunable superconducting capacitive coupler and an in-situ tunable superconducting inductive coupler, respectively. Tunable couplers provide diagonal and off-diagonal coupling. Compound Josephson junctions (CJJs) of the tunable couplers are responsive to a flux bias to tune a sign and magnitude of a sum of a capacitance of a fixed capacitor and a tunable capacitance which is mediated across a pair of coupling capacitors. The qubits may be hybrid qubits, operable in a flux regime or a charge regime. Qubits may include a pair of CJJs that interrupt a loop of material and which are separated by an island of superconducting material which is voltage biased with respect to a qubit body.