Diamond Magnetometry and Gradiometry Towards Subpicotesla dc Field Measurement

Nitrogen-vacancy (N-V) centers in diamond have developed into a powerful solid-state platform for compact quantum sensors. However, high-sensitivity measurements usually come with additional constraints on the pumping intensity of the laser and the pulse control applied. Here, we demonstrate high-sensitivity N-V-ensemble-based magnetic field measurements with low-intensity optical excitation. Direct current magnetometry methods such as continuous-wave optically detected magnetic resonance and continuously excited Ramsey measurements combined with lock-in detection are compared to achieve an optimization. Gradiometry is also investigated as a step towards unshielded measurements of unknown gradients. The magnetometer demonstrates a minimum detectable field of 0.3–0.7 pT in a 73-s measurement when a flux guide with a sensing dimension of 2 mm is applied, corresponding to a magnetic field sensitivity of 2.6–6 pT/√Hz. Combined with our previous efforts on diamond ac magnetometry, the diamond magnetometer is promising for performing wide-bandwidth magnetometry with picotesla sensitivity and a cubic-millimeter sensing volume under ambient conditions

< QC | HPC >: Quantum for HPC

Quantum Computing (QC) describes a new way of computing based on the principles of quantum mechanics. From a High Performance Computing (HPC) perspective, QC needs to be integrated: at a system level, where quantum computer technologies need to be integrated in HPC clusters; at a programming level, where the new disruptive ways of programming devices call for a full hardware-software stack to be built; at an application level, where QC is bound to lead to disruptive changes in the complexity of some applications so that compute-intensive or intractable problems in the HPC domain might become tractable in the future. The White Paper QC for HPC focuses on the technology integration of QC in HPC clusters, gives an overview of the full hardware-software stack and QC emulators, and highlights promising customised QC algorithms for near-term quantum computers and its impact on HPC applications. In addition to universal quantum computers, we will describe non-universal QC where appropriate. Recent research references will be used to cover the basic concepts. Thetarget audience of this paper is the European HPC community: members of HPC centres, HPC algorithm developers, scientists interested in the co-design for quantum hardware, benchmarking, etc