Optical Qubit Addressing with Parallel Beam Steering and Low Crosstalk
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Solution Overview
Problem
Scalable local control of gate operations for neutral atom quantum computing is challenging due to the need for uniform arrays of focused spots, rapid switching between illumination patterns, and low crosstalk between closely spaced sites, which existing technologies like MC-AOM, AODs, LCOS-SLMs, and DMDs have not adequately addressed.
Innovation Solution
A system combining an AOM, LCOS-SLM, and DMD is used to generate and steer laser beams, with a compensation grating to correct aberrations, enabling high-speed, low-crosstalk control of large-scale quantum gate operations by dividing a single input beam into secondary beams corresponding to qubit positions and using the DMD to selectively shutter them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If MC-AOM or AOM arrays are used to generate uniform arrays of focused spots, then manufacturing precision is improved, but device complexity increases when scaling to larger numbers of channels
Solution Approach 1:
The patent combines an AOD and LCOS-SLM into a single integrated system where the AOD generates a row of focused spots and the LCOS-SLM modulates them into an arbitrary 2D array pattern. This merging of functions reduces the need for multiple discrete components compared to using separate AOM arrays for both row and column addressing.
Solution Approach 2:
The patent segments the optical control into two functional stages: first using the AOD to create a 1D array of focused spots, then using the LCOS-SLM to independently modulate each spot's intensity and phase to form the final 2D pattern. This segmentation allows each component to be optimized for its specific function while working together to achieve complex patterns.
2Ease of operation
If AODs are used to address individual qubits, then ease of operation is improved for row or column addressing, but productivity decreases due to limited parallel control capability
Solution Approach 1:
The patent transitions from 1D row or column addressing using AODs to 2D arbitrary pattern addressing by combining AOD with LCOS-SLM. The AOD provides 1D spot generation while the LCOS-SLM adds a second dimension of control, enabling simultaneous addressing of multiple qubits in arbitrary 2D configurations and dramatically increasing parallel control capability.
3Adaptability or versatility
If LCOS-SLMs are used to generate arbitrary illumination patterns, then adaptability is improved, but speed decreases due to refresh rates of 60-120 Hz compared to intrinsic gate times
Solution Approach 1:
The patent segments the illumination control into two independent parts: the AOD handles high-speed temporal modulation at nanosecond scales for individual spot control, while the LCOS-SLM handles spatial pattern generation at lower frequencies. This segmentation allows each component to operate at its optimal speed for its specific function, with the AOD providing the necessary high-speed gating capability.
4Speed
If DMDs are used to generate sparse spot arrays, then speed is improved with fast switching, but manufacturing precision deteriorates due to poor efficiency in generating sparse patterns
Solution Approach 1:
The patent segments the optical control functions so that the AOD handles the generation of focused spots with precise positioning and uniformity, while the LCOS-SLM handles the intensity modulation and pattern formation. This segmentation allows the AOD to optimize for spot quality while the LCOS-SLM provides the necessary pattern flexibility and speed.
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
The system achieves high extinction ratios, uniform beam waist, and low crosstalk, allowing for efficient parallel gate operations on large-scale neutral atom arrays, suitable for quantum computing, quantum simulation, and other applications like trapped ions and solid-state defects.
Implementation Method 1
an optional first modulator (such as a high-speed acousto-optic modulator (AOM), or electro-optic modulator) configured to produce a single input beam of light comprising pulses of laser light
Implementation Method 2
a second modulator (such as a phase-only spatial light modulator (SLM) or an acoustic-optical deflector (AOD)) configured to imprint a phase pattern on a received single input beam
Implementation Method 3
after a lens positioned after the second modulator, the single input beam is divided into a pattern of secondary beams that correspond to the positions of the atoms or ions in a quantum computer, the lens after the second modulator being positioned so the secondary beams are focused to form an image
Implementation Method 4
a third modulator (such as a digital micromirror device (DMD) amplitude modulator) configured to shut off a subset of the secondary beams
Data Source
AI summary
Disclosed are systems and techniques for generating and steering laser beams onto atoms for performing locally addressed quantum gate operations. A system may include (i) a high-speed acousto-optic modulator (AOM) for producing a single input beam, (ii) a phase-only spatial light modulator (SLM) for imprinting a phase pattern on the single input beam, the phase pattern being chosen such that after a lens positioned after the SLM, the single input beam is divided into a pattern of secondary beams that correspond to the positions of the atoms or ions in a quantum computer, the lens after the SLM being positioned so the secondary beams are focused to form an image on a digital micromirror device (DMD) amplitude modulator, (iii) a compensation grating after the DMD, in the path of the secondary beams, and (iv) an objective lens after the compensation grating to image the secondary beams onto an atomic array.