Graphene is a newly discovered carbon based material just one atom thick with very unusual electronic properties.

At NPL we have studied these unusual electrical properties under very extreme conditions....

A quantum realisation of the ampere is required to demonstrate the internal consistency of the electrical units.

We are currently working on two possible routes to a quantum current standard.  One  involves controlled  pumping of single electrons through a semiconductor quantum dot.  The other aims to drive a controlled stream of Cooper pairs through a superconducting nanowire, via the phenomenon of quantum phase-slip.

Both approaches involve the design and fabrication of novel devices in collaboration with universities and other  research institutions.  Quantum dots and superconducting nanowires also have applications outside the field of  metrology, in particular for quantum information processing.

Underpinning a new breed of data security technologies - quantum key distribution

Driven by quantum information science, quantum photonics has developed significantly in recent years...

The quantum standard of voltage, based on the ac Josephson effect, is central to electrical metrology.

Our current aim is to provide traceability to quantum standards for sampled electrical measurements. Digital acquisition of waveforms is now commonplace yet there is no direct route for the verification and calibration of data converters to the quantum standard of voltage.

Using arrays of Josephson junctions, we are able to synthesize voltage waveforms as a series of discrete samples. The Josephson voltage reference gives us a perfectly linear scale and absolute accuracy dependent only on the frequency of the microwave power used to bias the junctions.

SQUIDs (Superconducting QUantum Interference Devices) are macroscopic quantum objects which are capable of detecting and measuring a wide range of physical parameters with unequalled sensitivity.

Research at NPL aims to develop devices for a range of applications, from single photon spectroscopy, through NEMS readout, nanomagnetic particle detection and characterisation of ion micro-beams for dosimetry.

We have developed a range of experimental techniques for measurements and visualisation of small magnetic fields/moments.

Superconducting micro-resonators are capable of coupling to and reading out various quantum devices (such as SQUIDs and qubits). At NPL we employ these micro-resonators to probe sources of noise.

At temperatures below 1K this noise can be parameterised as a bath of two level fluctuators (TLFs). We are currently working on applying precision frequency metrology techniques and analysis to our solid-state system to measure noise due to TLFs within a variety of systems.

Devices are fabricated in collaboration with NTT (Japan) and Royal Holloway University. It is hoped that a greater understanding of noise within the dielectric environment would be beneficial to many devices used for quantum information processing, including qubits, SQUIDs, NEMs and kinetic inductance detectors.

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