Constructing a modular microwave trapped-ion quantum computer demonstrator device

Introduction Trapped ions are a promising tool for building a large-scale quantum computer. We present a blueprint for a scalable architecture based on trapped-ion quantum computer modules [1]. These modules are designed for... [ view full abstract ]

Introduction

Trapped ions are a promising tool for building a large-scale quantum computer. We present a blueprint for a scalable architecture based on trapped-ion quantum computer modules [1]. These modules are designed for the implementation of a quantum gate technology based on global long-wavelength radiation fields and voltages applied to a microchip. The design makes use of ion transport between adjacent modules, thereby allowing arbitrarily many modules to be connected in a fast and robust way to construct a large-scale device.

Methods

To prove the feasibility of our modular architecture we are building a demonstrator device to implement high-fidelity quantum gate operations and ion transport between two modules. By fabricating chips with a well-defined cleaved edge it is possible to physically ‘tile’ together two or more devices to create a continuous trapping potential across their interface. We use on-chip structures to generate large magnetic field gradients to achieve fast and high fidelity gates, and a scalable cooling system to reduce ion heating rates and improve thermal management of the devices.

Results

We present progress toward the development of our demonstrator device. By using silicon microfabrication techniques we have produced ion-trap microchips featuring alignable edge electrodes and initial test structures with integrated current carrying wires for generating magnetic field gradients. Testing has shown that these structures can sustain high currents, capable of producing a gradient of >180 T/m to support fast and high fidelity quantum logic operations. We show a proof-of-principle UHV piezo positioning system with a travel range of 600 µm and <0.1 µm resolution in all axes to permit the interconnection of modules via ion-shuttling. In addition we present a scalable cryogenic helium gas circulation system design capable of cooling multiple modules and we will show initial test results of the commissioned system.

Discussion

The successful realisation of this demonstrator device will make a significant step towards constructing larger scale devices based on inherently scalable microwave technology and ion shuttling operations. This will pave the way for the realisation of error correcting codes and more general quantum algorithms with a large number of trapped ions.

[1] Blueprint for a microwave trapped ion quantum computer, B. Lekitsch, S. Weidt, A.G. Fowler, K. Mølmer, S.J. Devitt, Ch. Wunderlich, and W.K. Hensinger, Science Advances 3, e1601540 (2017)