Scalable low-latency feedback control device for quantum bits

Abstract

The invention discloses a scalable low-latency feedback control device for quantum bits. The device realizes the feedback control of the quantum states of multiple quantum bits by means of digital signal processing technology and a quantum mechanical principle based on a high-speed microwave baseband signal transceiving hardware circuit board. The quantum feedback control device designed in the present invention is different from the feedback control applied in the classic field, and can generate synchronous microwave pulses for operating superconducting quantum bits, can accurately define thenumber of times, the time and the strength of quantum measurement, demodulates measurement signals in real time, deploys a quantum feedback algorithm on an FPGA, and has extremely low feedback delayand excellent scalability so as to accurately control a system integrating multiple quantum bits and to satisfy a requirement for running a measurement-based quantum error correction algorithm on a quantum chip.

Description

technical field [0001] The invention belongs to the field of quantum control, and in particular relates to a scalable and low-delay feedback control device for qubits, which is a microwave device for measurement and feedback control of scalable qubit chips. Background technique [0002] With the maturity of micro-processing technology and quantum information technology, how to accurately observe and control artificial quantum systems has become the focus of research and development in the academic and industrial circles. The object of quantum control is a superconducting qubit chip, which works in a low-temperature environment to maintain the superconducting state of the material (about 20m kelvin), and integrates several quantum bits (quantumbit hereinafter referred to as qubit) on the chip. Each qubit is an artificial two-level quantum system. By precisely adjusting the frequency, amplitude and phase of the electromagnetic field input to the chip, the qubit can be controll...

AI Technical Summary

Problems solved by technology

In order to keep the quantum state of the target bit from being destroyed during the measurement and control process, the academic community has proposed two feasible methods: one is to perform "weak measurement" on a single bit, that is, to finely control the time and length of the measurement pulse, and obtain However, in the existing reports, although the adjustment of the measurement intensity and the adjustment of the measurement time window are used to analyze the weak measurement on the computer, it is not possible to process the obtained numbers in real time. Signal and feedback control; the other is to encode multiple bits, by measuring the auxiliary qubit, to achieve the state of the logic qubit without destroying the state while performing feedback calibration on its state

However, this technology is limited to the single-bit range and does not extend to multi-bit feedback control

On the other hand, commercial instruments with quantum control have single functions, such as the AWG7000 series arbitrary waveform generator from Tektronix, Switzerland, and the UHF digital converter kit from Zurich Instruments, Switzerland, which only support the generation of control waveforms and simple conditional trigger functions, feedback delay If it is greater than 500ns, the solution cannot be applied to the quantum regulation of more than 20 qubits

[0007] Numerous studies have shown that quantum feedback control based on microwave measurement and control technology has the advantages of high precision and small delay. Feedback control with multiple parameter-controllable measurements is not seen for multi-bit systems

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