arXiv subjects

G Andrew D Briggs

Publications and source records attributed to G Andrew D Briggs.

4 recordsLinked to original sources

arXiv2024

Reconfigurable multiplex setup for high throughput electrical characterisation at cryogenic temperature

In this paper, we present a reconfigurable multiplex (MUX) setup that increases the throughput of electrical characterisation at cryogenic temperature. The setup separates the MUX circuitry from quantum device under test (qDUT), allowing qDUT chips to be exchanged easily and MUX chips to be reused. To interface with different types of qDUTs, board-level designs are incorporated to allow interconnects flexibly routed into different topology. MUXs are built based on a multiple level selective gating (MLSG) scheme, where the number of multiplexed output channels (interconnects) is exponentially dependent on the number of control lines. In the prototype setup presented in this paper, with 14 out of 44 existing wires from room temperature, 4 MUXs at cryogenic temperature can supply in total 128 interconnects to interface with qDUTs. We validate the MUX setup operation and assess the various limits existed by measuring k$Ω$ resistors made of $μ$m-size graphene ribbons. We further demonstrate the setup by performing charge transport measurement on 128 nm-size graphene quantum devices in a single cooling down.

cond-mat.mes-hall↗

arXiv2024

Parallel refreshed cryogenic charge-locking array with low power dissipation

To build a large scale quantum circuit comprising millions of cryogenic qubits will require an efficient way to supply large numbers of classic control signals. Given the limited number of direct connections allowed from room temperature, multiple level of signal multiplexing becomes essential. The stacking of hardware to accomplish this task is highly dependent on the lowest level implementation of control electronics, of which an open question is the feasibility of mK integration. Such integration is preferred for signal transmission and wire interconnection, provided it is not limited by the large power dissipation involved. Novel cryogenic electronics that prioritises power efficiency has to be developed to meet the tight thermal budget. In this paper, we present a power efficient approach to implement charge-locking array.

quant-ph↗

arXiv2006

Direct optical excitation of a fullerene-incarcerated metal ion

The endohedral fullerene Er3N@C80 shows characteristic 1.5 micron photoluminescence at cryogenic temperatures associated with radiative relaxation from the crystal-field split Er3+ 4I13/2 manifold to the 4I15/2 manifold. Previous observations of this luminescence were carried out by photoexcitation of the fullerene cage states leading to relaxation via the ionic states. We present direct non-cage-mediated optical interaction with the erbium ion. We have used this interaction to complete a photoluminescence-excitation map of the Er3+ 4I13/2 manifold. This ability to interact directly with the states of an incarcerated ion suggests the possibility of coherently manipulating fullerene qubit states with light.

quant-ph↗

arXiv2005

Towards a fullerene-based quantum computer

Molecular structures appear to be natural candidates for a quantum technology: individual atoms can support quantum superpositions for long periods, and such atoms can in principle be embedded in a permanent molecular scaffolding to form an array. This would be true nanotechnology, with dimensions of order of a nanometre. However, the challenges of realising such a vision are immense. One must identify a suitable elementary unit and demonstrate its merits for qubit storage and manipulation, including input / output. These units must then be formed into large arrays corresponding to an functional quantum architecture, including a mechanism for gate operations. Here we report our efforts, both experimental and theoretical, to create such a technology based on endohedral fullerenes or 'buckyballs'. We describe our successes with respect to these criteria, along with the obstacles we are currently facing and the questions that remain to be addressed.

quant-ph↗