Libre-QASIC

Libre-QASIC is a test chip designed to test the functionality of the our optical quantum components on the Skywater 130 pdk. It seeks to develop a number of optical components in CMOS technology needed to manufacture affordable quantum ASICs with existing technologies.

Note: This is our first attempt at implementing quantum gates in CMOS technology, it is expected that some of these experimental structures will fail. After component testing and validation, useful libraries necessary for design and manufacturing will be provided free of charge and under a GPLv3 license on our Github.

Chip Features

1. A state-selectable attenuated single photon source with P(x) > 0.8
2. Single photon detector (Implemented via SPAD)
3. Si-based optical wave guide.
4. Optical Attenuator & Trap
5. 50/50 Polarizing beam splitter.
6. Hadamard Gate
7. Pauli-X Gate (Optical NOT Gate)
8. Pauli-Z Gate (Optical Phase Shift Gate)
9. Controlled-Z Gate (Phase Controlled Entanglement Gate)
10. Controlled-X Gate (State Controlled Entanglement Gate)
11. Measure Gate (Dual SPS With Comparator Readout)
12. 32 Qubit Q-Blur Implementation with P(x) > 0.1

Project Goals

The primary goal of Libre-QASIC is to validate Spooky Manufacturing's open-source universal quantum logic gates and develop open-source libraries that can be integrated into existing manufacturing processes. By making this open-source, we hope to enable the production of affordable quantum technologies for consumer devices.

Tertiary goals for this project are to drive the development of new open-source tools that will assist developers in the design, layout, and production of quantum ASICS such as our OpenQASM synthesizer QEDA and SpookyIDE, our quantum hardware development enviroment.

How Our Circuits Work

The technology we are using is based on the KLM protocol. We utilize single-photons for their quantum properties such as superposition. To represent the traditional spin-state of a qubit, our photonic qubits are polarization encoded in a linear circuit of two polarization modes (Horizontal and Vertical). These are analogous to the typical bits one is used to working with in digital logic. Our photonic qubits can therefore be in either the H (1) or V (0) modes. Due to the wave-particle properties of light, the photons can also pass through both modes silmutaneously (known as a superposition). The intensity of a photon in either mode is directly related to the probability of the photon collapsing into one or the other mode. Quantum logic gates are created by careful arrangement of optical components such as phase shifts (which delay a photon, creating a Z rotation about the bloch sphere), beam splitters and mirrors (which change the position of a photon in the circuit providing for X rotation about the bloch sphere), or complex arrays of these components to create entangled states between multiple photons. When the photon finally reaches the end of a given circuit, both modes will be measured by single photon detectors which collapse the probability wave and our qubit is finally converted into a digital bit.

A quantum circuit then consists of a minimum of components: a single photon source, two wave guides per qubit, one quantum logic gate which manipulates either the state, phase, or entangles (or any combination of the three), followed by a final measurement gate.

These quantum circuits are inherently probabilistic and require multiple iterations of a circuit to succeed, the exact number required is dependent on the number and type of gates used as well as the overall circuit length.