Quantum Microwave, a microwave and millimeter-wave components supplier and manufacturer out of Massachusetts, has introduced the QMC-JPA-MCA01 assembly. It is a convenient package that includes all the required cryogenic components to operate the Raytheon/BBN 5 – 7 GHz Wide Bandwidth Josephson Parametric Amplifier (JPA). This assembly is intended to be a cryogenic turn-key solution, saving the end-user time and money on design, development, and validation of the auxiliary cryogenic circuitry, which is required before near-quantum limited noise measurements with the JPA can be performed.
Out of the box, the QMC JPA Assembly is designed to be installed onto the mixing chamber plate of a dilution refrigerator and is compatible with standard RF microwave readout chains found in cryogenic measurement setups used to characterize superconducting devices. Each QMC JPA Assembly is fully characterized at < 20 mK before being shipped to determine tuning parameters for gain and noise. A datasheet with measurement data is provided with each QMC JPA Assembly to aid the end-user in tuning up the JPA for the first time.
This assembly provides a gain of more than 20 dB with an instantaneous bandwidth of 300 MHz and has a noise temperature of 295 mK (at 6.8 GHz). It comes in a compact Aluminum cryo-package with 50-ohm matched input and 2.92 mm input/output connectors.
Figure 1: (Left Panel) High level functional diagram of the QMC JPA Assembly. (Right Panel) Port labels of the QMC JPA Assembly
The QMC JPA Assembly comprises a cryogenic circuit built around the JPA to facilitate its operation. The JPA is a one-port amplifier; the weak signal to be amplified and the amplified signal are both incident and originate from the same port. The cryogenic circuit of the QMC JPA Assembly routes the input and output signals to different ports, aiding the integration into standard RF readout chains. A high-level functional diagram of the QMC JPA Assembly is shown in Figure 1.
The cryogenic circuit for the QMC JPA Assembly is shown in Figure 2. This circuit is composed of a cryogenic Low Noise Factory's circulator LNF-CIC4_8A, Quantum Microwave's bias-Tee QMC-CRYOTEE-0.218SMA-FFF, Quantum Microwave's LC/Infrared Eccosorb filter combination QMC-CLCE-160AFF, and Raytheon/BBN JPA #BBN-PS2-JPA-DEVICE-QEC. Critical for JPA performance is the impedance the JPA sees at its single port. In the circuit, the JPA is matched to a cryogenic circulator through a short ~2.5” low-loss cable to minimize the standing waves and achieve the JPA's desired performance.
Figure 2: (Left Panel) QMC JPA Assembly with the magnetic shield removed. (Right Panel) Circuit schematic of the QMC JPA Assembly.
The JPA is based on a Superconducting Quantum Interference Device (SQUID), which is very sensitive to external magnetic fields. To minimize the impact of external magnetic field fluctuations in the environment, the JPA in the QMC JPA Assembly is magnetically shielded with a mu-metal can made from A4K proprietary alloy from Amuneal Manufacturing Corporation. To minimize potential offsets in current bias tuning of the JPA or hysteretic effects, all components inside the mu-metal can are non-magnetic. The tuning bias of the JPA is provided to the QMC JPA Assembly through the port labeled DC. In the QMC JPA assembly, the DC bias is filtered by the QMC-CLCE-160AFF filter, which provides a cutoff frequency of 160 MHz. The filter is also encapsulated with an Eccosorb infrared absorber, which provides strong attenuation to the infrared.
Click here for more details on the QMC-JPA-MCA01 assembly from Quantum Microwave.
Click here for more details on the Wide Bandwidth Josephson Parametric Amplifier (JPA) from Raytheon BBN.
