Microwave measurement beyond the quantum limit with a nonreciprocal amplifier

Abstract

The measurement of a quantum system is often performed by encoding its state in a single observable of a light field. The measurement efficiency of this observable can be reduced by loss or excess noise on the way to the detector. Even a \textit{quantum-limited} detector that simultaneously measures a second non-commuting observable would double the output noise, therefore limiting the efficiency to $50\%$. At microwave frequencies, an ideal measurement efficiency can be achieved by noiselessly amplifying the information-carrying quadrature of the light field, but this has remained an experimental challenge. Indeed, while state-of-the-art Josephson-junction based parametric amplifiers can perform an ideal single-quadrature measurement, they require lossy ferrite circulators in the signal path, drastically decreasing the overall efficiency. In this paper, we present a nonreciprocal parametric amplifier that combines single-quadrature measurement and directionality without the use of strong external magnetic fields. We extract a measurement efficiency of $62_{-9}^{+17}\%$ that exceeds the quantum limit and that is not limited by fundamental factors. The amplifier can be readily integrated with superconducting devices, creating a path for ideal measurements of quantum bits and mechanical oscillators.

arXiv comment12 pages, 9 figures

References in corpus (24)

• Cavity Optomechanics
• Introduction to Quantum Noise, Measurement and Amplification
• Quantum information processing with circuit quantum electrodynamics
• High-fidelity preparation, gates, memory and readout of a trapped-ion quantum bit
• Nonreciprocal Photon Transmission and Amplification via Reservoir Engineering
• Nanomechanical motion measured with precision beyond the standard quantum limit
• Quantum feedback control of a superconducting qubit: Persistent Rabi oscillations
• Measurement-based quantum control of mechanical motion
• A widely tunable parametric amplifier based on a SQUID array resonator
• Realizing Rapid, High-Fidelity, Single-Shot Dispersive Readout of Superconducting Qubits
• Observation of measurement-induced entanglement and quantum trajectories of remote superconducting qubits
• Quantum back-action of variable-strength measurement
• Generating Entangled Microwave Radiation Over Two Transmission Lines
• Quantum nondemolition measurement of a nonclassical state of a massive object
• The reconfigurable Josephson circulator/directional amplifier
• Nonreciprocal microwave signal processing with a Field-Programmable Josephson Amplifier
• On-chip superconducting microwave circulator from synthetic rotation
• Graph-based analysis of nonreciprocity in coupled-mode systems
• Directional amplification with a Josephson circuit
• Reversing quantum trajectories with analog feedback
• Comparing and combining measurement-based and driven-dissipative entanglement stabilization
• Realization of directional amplification in a microwave optomechanical device
• Quantum Bayesian approach to circuit QED measurement with moderate bandwidth
• Generation and efficient measurement of single photons from fixed frequency superconducting qubits

Cited by in corpus (11)

• Microwaves in Quantum Computing
• Synthesis of parametrically-coupled networks
• Restoration of the non-Hermitian bulk-boundary correspondence via topological amplification
• Primary thermometry of propagating microwaves in the quantum regime
• Efficient qubit measurement with a nonreciprocal microwave amplifier
• Efficient and Low-Backaction Quantum Measurement Using a Chip-Scale Detector
• Nonlinearity and Parametric Amplification of Superconducting Nanowire Resonators in Magnetic Field
• Floquet theory for temporal correlations and spectra in time-periodic open quantum systems: Application to squeezed parametric oscillation beyond the rotating-wave approximation
• Constraints on Gaussian Error Channels and Measurements for Quantum Communication
• Fully Directional Quantum-limited Phase-Preserving Amplifier
• Non-reciprocal scattering in a microwave frequency comb