Quantum noise spectroscopy as an incoherent imaging problem

Quantum noise as an entanglement meter.

Transport in a quantum point contact (QPC) can be used to generate many-body entanglement of Fermi seas in the leads. A universal relation is found between the generated entanglement entropy and the fluctuations of electric current, which is valid for any protocol of driving the QPC. This relation offers a basis for direct electric measurement of entanglement entropy. In particular, by utilizin...

Multiqubit Spectroscopy of Gaussian Quantum Noise

We introduce multi-pulse quantum noise spectroscopy protocols for spectral estimation of the noise affecting multiple qubits coupled to Gaussian dephasing environments including both classical and quantum sources. Our protocols are capable of reconstructing all the noise autoand cross-correlation spectra entering the multiqubit dynamics. We argue that this capability is crucial not only for met...

Quantum-noise-limited optical frequency comb spectroscopy.

We achieve a quantum-noise-limited absorption sensitivity of 1.7×10(-12) cm(-1) per spectral element at 400 s of acquisition time with cavity-enhanced frequency comb spectroscopy, the highest demonstrated for a comb-based technique. The system comprises a frequency comb locked to a high-finesse cavity and a fast-scanning Fourier transform spectrometer with an ultralow-noise autobalancing detect...

Incoherent Quantum Control

Conventional approaches for controlling open quantum systems use coherent control which affects the system’s evolution through the Hamiltonian part of the dynamics. Such control, although being extremely efficient for a large variety of problems, has limited capabilities, e.g., if the initial and desired target states have density matrices with different spectra or if a control field needs to b...

Noise as an environmental problem in the animal house.