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arXiv:1403.4465 · Physical Review B

Nonabsorbing high-efficiency counter for itinerant microwave photons

Bixuan Fan, Göran Johansson, Joshua Combes, Gerard J Milburn, Thomas M. Stace

Published Jul 25, 2014• 40 citations
arXivHTMLPDF

Abstract

Detecting an itinerant microwave photon with high efficiency is an outstanding problem in microwave photonics and its applications. We present a scheme to detect an itinerant microwave photon in a transmission line via the nonlinearity provided by a transmon in a driven microwave resonator. With a single transmon we achieve 84% distinguishability between zero and one microwave photons and 90% distinguishability with two cascaded transmons by performing continuous measurements on the output field of the resonator. We also show how the measurement diminishes coherence in the photon number basis thereby illustrating a fundamental principle of quantum measurement: The decoherence rate increases as the detector is made more effective.

DOI
10.1103/physrevb.90.035132

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Detecting an itinerant microwave photon with high efficiency is an outstanding problem in microwave photonics and its applications. We present a scheme to detect an itinerant microwave photon in a transmission line via the nonlinearity provided by a transmon in a driven microwave resonator. With a single transmon we achieve 84% distinguishability between zero and one microwave photons and 90% distinguishability with two cascaded transmons by performing continuous measurements on the output field of the resonator. We also show how the measurement diminishes coherence in the photon number basis thereby illustrating a fundamental principle of quantum measurement: The decoherence rate increases as the detector is made more effective.
Detecting an itinerant microwave photon with high efficiency is an outstanding problem in quantum optics at microwave frequencies and in the fundamental quantum mechanics experimental toolbox. This subject has attracted a lot of attention and there are growing number of excellent experimental demonstrations and theoretical proposals towards this aim. However, due to the extremely low energy of microwave quanta, efficiently detecting a propagating microwave photon in a non-absorbing manner is still an unresolved challenge and it is the focus of the major part of this thesis. Motivated by a recent experiment that shows a superconducting artificial atom (a transmon) in a one-dimensional microwave transmission line exhibits gigantic cross-Kerr nonlinearities, 1000 times larger than in comparable optical systems, I investigate the possibility of detection single microwave photons using a transmon induced cross-Kerr-like interaction between two microwave fields. The photon number in one field is inferred through the measurement of the displacement of the other field. The first project on this subject is to investigate the feasibility of detecting a single microwave photon with signal-to-noise ratio (SNR) greater than unity using a three-level approximation for the transmon in an open transmission line, due to the saturation of transmon response to the probe intensity. After that, an improved scheme was proposed to overcome the limitations in the preceding work. By using a cavity probe field the signal photon induced probe displacement is strongly enhanced. Further additional transmon-cavity units can be cascaded to further improve the detection efficiency. It is shown that with only two transmons the distinguishability to resolve a single-photon state from the vacuum is up to 90%90\%90%. One advantage of this photon detection scheme is that it does not rely on the absorption of single microwave photons, which enables repeated measurements and further applications. Moreover, I also show how the measurement diminishes coherence in the photon number basis thereby illustrating a fundamental principle of quantum measurement: the higher the measurement efficiency, the greater is the decoherence. Apart from the investigation on the single microwave photon detection, this thesis also studies nonlinear dynamics of a hybrid coupled-resonator and opto-mechanical system. It is shown that the saddle-node bifurcation and the Hopf bifurcation appear in the system, which leads to bistability and limit cycle dynamics of the mechanical position and the output light intensity. More importantly, the opto-mechanical nonlinearity dramatically changes the transparency window of the coupled resonator induced transparency (CRIT) and based on the narrow and bistable CRIT transparency window, the proposed system is shown to be a good platform for the weak impulsive force detection with a good sensitivity.
Single photon detection is a key resource for sensing at the quantum limit and the enabling technology for measurement-based quantum computing.Photon detection at optical frequencies relies on irreversible photoassisted ionization of various natural materials.However, microwave photons have energies 5 orders of magnitude lower than optical photons, and are therefore ineffective at triggering measurable phenomena at macroscopic scales.Here, we report the observation of a new type of interaction between a single twolevel system (qubit) and a microwave resonator.These two quantum systems do not interact coherently; instead, they share a common dissipative mechanism to a cold bath: the qubit irreversibly switches to its excited state if and only if a photon enters the resonator.We have used this highly correlated dissipation mechanism to detect itinerant photons impinging on the resonator.This scheme does not require any prior knowledge of the photon waveform nor its arrival time, and dominant decoherence mechanisms do not trigger spurious detection events (dark counts).We demonstrate a detection efficiency of 58% and a record low dark count rate of 1.4 per millisecond.This work establishes engineered nonlinear dissipation as a key enabling resource for a new class of low-noise nonlinear microwave detectors.
The realization of a high-efficiency microwave single photon detector is a long-standing problem in the field of microwave quantum optics. Here, we propose a quantum nondemolition, high-efficiency photon detector that can readily be implemented in present state-of-the-art circuit quantum electrodynamics. This scheme works in a continuous fashion, gaining information about the photon arrival time as well as about its presence. The key insight that allows us to circumvent the usual limitations imposed by measurement backaction is the use of long-lived dark states in a small ensemble of inhomogeneous artificial atoms to increase the interaction time between the photon and the measurement device. Using realistic system parameters, we show that large detection fidelities are possible.
We present a novel scheme to detect itinerant microwave radiation at the single photon level. Using existing Josephson-photonics devices, where two microwave cavities are coupled by a dc-voltage biased superconducting junction, we theoretically show how to implement a stroboscopically repeated, near-projective measurement of a photon impinging on one of the cavities. Optimizing rate, duration, and strength of the measurement by flux control of the junction and developing a threshold protocol to detect the photon from a homodyne measurement of the radiation output of the other cavity, we achieve highly efficient detection with low dark counts. By cascading the detector with a preamplifier, where a similar two-cavity Josephson-photonics device acts as a photon multiplier, we can further improve the device to reach a detection efficiency of 88.5%88.5 \%88.5% with a dark count rate of ∼10−4γa\sim10^{-4} γ_a∼10−4γa​, set by the resonance width γaγ_aγa​ of the absorbing cavity. These results for a multiplication factor of two suggest that near-unity efficiencies may be reached for higher multiplication factors.
We present a scheme for microwave photon detection via cross Kerr nonlinearity between two microwave modes mediated by a transmon. Using a cascaded, stochastic master equation method and conditional measurement simulations, we analyze the dependence of the probe phase shift on the control photon number. We demonstrate here that for a microwave pulse with a few photons (below 10), the relationship between the phase shift and the photon number is almost linear. Also, in our scheme, microwave photons to be detected are guided by a 1D transmission line, rather than a cavity, making it suitable for a wide range of frequencies. Finally, the signal-noise-ratio (SNR) and the feasibility of this scheme for experimental realization are discussed. Our scheme might help to build a practical photon detector in the microwave regime.