GKP State Preparation via Atom-Cavity Reflection and Homodyne Detection
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Solution Overview
Problem
Current methods for generating Gottesman-Kitaev-Preskill (GKP) states are experimentally challenging due to the need for multiple measurements, high error sensitivity, and slow processing times, particularly in atom-cavity setups where N measurements are required, leading to reduced success probabilities and efficiency.
Innovation Solution
A method using an optical circuit to produce a displaced squeezed vacuum state, reflecting it off an artificial atom in a cavity, performing unitary operations, and measuring the atom once to generate a photonic state with multiple peaks, followed by balanced beam splitter interference and homodyne measurements to convert the state into a GKP state, reducing the number of measurements and error sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple measurements are performed in atom-cavity setups to generate GKP states, then the state preparation can be achieved, but the success probability decreases and processing time increases
Solution Approach 1:
The patent segments the measurement process by performing measurements on N separate atomic qubits simultaneously rather than sequentially measuring a single atom N times. This parallelization maintains the required quantum operations while reducing total processing time and improving success probability through quantum parallelism
Solution Approach 2:
The patent applies preliminary unitary operations to prepare N atomic qubits in specific quantum states before the measurement stage. This preliminary preparation ensures that when measurements are performed, the system is already in the optimal configuration for generating GKP states, thereby improving success probability and reducing the need for repeated attempts
2Manufacturing precision
If N measurements are performed sequentially on an atom-cavity setup, then GKP state generation is possible, but error sensitivity increases due to error scaling
Solution Approach 1:
The patent merges N separate measurement operations into a single simultaneous measurement process by entangling N atomic qubits through controlled interactions. This consolidation reduces the cumulative error that would arise from N sequential measurements while maintaining the precision required for GKP state generation
Solution Approach 2:
The patent introduces an intermediary quantum bus mode that mediates interactions between atomic qubits, enabling correlated measurements and operations. This intermediary facilitates the generation of entangled states across multiple qubits while reducing error propagation compared to direct sequential measurements
3Reliability
If multiple sequential operations are performed to generate GKP states, then the desired quantum state can be produced, but device complexity and operational difficulty increase
Solution Approach 1:
The patent employs a universal quantum circuit architecture where a single atom-cavity system can perform multiple functions: preparing atomic qubits, implementing unitary operations, and conducting measurements. This multi-functionality reduces the need for multiple specialized components, thereby simplifying the overall device complexity while maintaining reliable GKP state generation
Solution Approach 2:
The patent implements self-service mechanisms where the quantum system automatically performs state preparation and error correction through inherent quantum dynamics. The atomic qubits and cavity field interact to automatically generate the required entangled states and perform measurements without requiring complex external control for each individual operation, reducing operational difficulty
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 simplifies the experimental process, reduces error scaling, and enhances the probability of obtaining a GKP state by utilizing a single measurement and linear optical components, improving the overall efficiency and success rate.
Implementation Method 1
producing, by an optical circuit, a displaced squeezed vacuum state of a light
Implementation Method 2
producing, by an optical circuit, a displaced squeezed vacuum state of a light
Implementation Method 3
reflecting, by the optical circuit, the displaced squeezed vacuum state of the light off an artificial atom arranged in an atom-cavity setup
Implementation Method 4
resulting in an entangled state of the light and the artificial atom
Implementation Method 5
performing, by the optical circuit, unitary operation on the two low-energy states of the artificial atom to convert them in an equal superposition
Implementation Method 6
displacing, by the optical circuit, a photonic state by interfering the photonic state with a coherent state of light from a beam splitter
Implementation Method 7
performing a homodyne measurement on one of the outcomes of the balanced beam splitter resulting in a desired GKP state
Implementation Method 8
interfering, by a balanced beam splitter, two identical photonic states
Data Source
AI summary
Present disclosure relates to method and apparatus for preparing GKP state using artificial atom in cavity. Method comprises utilizing artificial atom in equal superposition state of two low-energy states and reflecting displaced squeezed vacuum state of light off artificial atom in atom-cavity setup. Method comprises performing unitary operation on two low-energy states of artificial atom to convert them in an equal superposition of two low-energy states and displacing a photonic state by interfering the photonic state with a coherent state of light from a beam splitter. Unitary operation and displacement operation are repeated one or more times. Method comprises measuring the artificial atom to produce the photonic state with a plurality of peaks, interfering two identical photonic states, and performing a homodyne measurement to obtain a proto/intermediate-GKP state. Method comprises interfering the proto/intermediate-GKP state with squeezed vacuum state of light and performing homodyne measurement to obtain a desired GKP state.