Measurement-device-independent quantum key distribution (MDIQKD) protocol is immune to all attacks on detection and guarantees the information-theoretical security even with imperfect single-photon detectors. Recently, several proof-of-principle demonstrations of MDIQKD have been achieved. Those experiments, although novel, are implemented through limited distance with a key rate less than $0.1\mathrm{bit}/\mathrm{s}$. Here, by developing a 75 MHz clock rate fully automatic and highly stable system and superconducting nanowire single-photon detectors with detection efficiencies of more than 40%, we extend the secure transmission distance of MDIQKD to 200 km and achieve a secure key rate 3 orders of magnitude higher. These results pave the way towards a quantum network with measurement-device-independent security.

The main type of obstacles of practical applications of quantum key distribution (QKD) network are various attacks on detection. Measurement-device-independent QKD (MDIQKD) protocol is immune to all these attacks, and thus, a strong candidate for network security. Recently, several proof-of-principle demonstrations of MDIQKD have been performed. Although novel, those experiments are implemented in the laboratory with secure key rates less than 0.1 b/s. Besides, they need manual calibration frequently to maintain the system performance. These aspects render these demonstrations far from practicability. Thus, justification is extremely crucial for practical deployment into the field environment. Here, by developing an automatic feedback MDIQKD system operated at a high clock rate, we perform a field test via deployed fiber network of 30 km total length achieving a 16.9 b/s secure key rate. The result lays the foundation for a global quantum network, which can shield from all the detection-side attacks.

Commissioning of detector systems for the High-Luminosity Large Hadron Collider (HL-LHC) is scheduled to take place between 2026 and 2028 at CERN. Application Specific Integrated Circuits (ASICs) for those systems have been in intense development over the past ten years. Some of those ASICs, as is the case of the Low Power GigaBit Transceiver (lpGBT) described in this work, have now been produced in industrial quantities and have been fully qualified for operation in the HL-LHC environments that require, where the innermost detectors are concerned, radiation hardness in excess of 1 MGy. The lpGBT is a multi-functional device, enabling data transmission between the off-detector and the on-detector systems. Data can be transmitted from the detector at 5.12 Gbit s ⁻¹ and 10.24 Gbit s ⁻¹ and to the detector at 2.56 Gbit s ⁻¹ . It implements data rate-configurable electrical links to communicate with the front-end ASICs and low-speed serial and parallel buses for experiment control. A set of analog functions for monitoring and control of the physics detectors is also included. This paper describes the functionality and the architecture of the lpGBT ASIC and reports on its radiation hardness characterization.

We present a high-quality bias-free quantum random number generator (QRNG) using photon arrival time selectively, in accordance with the number of photon detection events within a sampling time interval in attenuated light. It is well shown in both theoretical analysis and experimental verification that this random number production method eliminates both bias and correlation perfectly without more postprocessing and that the random number can clearly pass the standard randomness tests. We fulfill theoretical analysis and experimental verification of the method whose rate can reach up to 45 Mb/s.

In high-precision detector systems, the power supply usually need to be ultra-low noise and stabilized. Design and implementation of an ultra-low noise power supply is described in this paper. We implemented and tested the power system actually in a scientific CCD (Charge-coupled device) detector system, but the design structure could be used in many high-precision detector systems as infrared detector or high-energy particles detectors. The power system uses DC-DC switching regulators and LDO regulators for power generating, uses multi-stage filters for noise reducing. Multi-output power supply with noise about 40 is achieved, the overall energy efficiency is 68.5%. Besides, the electronic system takes the low temperature as an important consideration, and the system has been tested in an extreme environment as low as 193 K.

This paper presents the designs and test results of two radiation tolerant 4 × 10 Gb/s vertical cavity surface emitting laser (VCSEL) array drivers VLAD and lpVLAD, both fabricated in a 1.2 V 65 nm CMOS technology. VLAD adopts a power efficient bandwidth-boost technology, and lpVLAD employs a novel high-efficiency output structure to achieve an ultra-low power consumption of 2.2 mW/Gb/ch with 2 mA bias current and 6 mA modulation current. Both drivers are optically tested passing 10 Gb/s eye mask with all channels active under the radiation of a total dose up to 350 Mrad(SiO₂).