Quantum theory of noise

S. M. Dutra, Krista Joosten, Gerard Nienhuis +1 more

We present a quantum theory of excess noise in lasers based on the concept of mode nonorthogonality. This theory incorporates the dynamics of the medium and can be used as a general starting point for dealing with excess noise in any laser, not just linear class-A lasers as in current theories of excess noise.

François Chapeau-Blondeau

Daniele Cuomo

Edward Tong, Paul Grimes, Lingzhen Zeng

Tucker's Quantum Theory of Mixing (QTM) is widely used to model the conversion gain and noise temperature of SIS mixers. In particular, the theory describes the phenomenon of non-classical conversion gain and that of infinite or even negative output impedances in inductively tuned SIS mixers. Common microwave noise theory is inadequate to describe the operation of the IF circuit connected to such mixers. In this paper, we report the use of the noise wave formalism to model the noise properties of a Double-Side-Band SIS mixer together with an IF isolator and low noise amplifier cascade. Starting from QTM, we derive the 4 noise parameters of the SIS mixer, together with an approximate 2-port chain matrix with an upper-side-band RF input port and an IF output port. These matrices are cascaded with the noise correlation matrix of the IF circuit to form a complete noise model of the SIS receiver. Optimum source impedance for the receiver can be derived from this noise model, which can be used in efficient CAD modeling of a complete SIS receiver.

Jincheng Zhang

This paper introduces a novel Quantum Decoherence Control Theory aimed at enhancing coherence times in quantum states through precise environmental noise management. The core mechanism relies on analyzing the impact of environmental noise on quantum states, utilizing quantum information theory and noise theory foundations to design targeted control strategies. Specifically, the theory proposes feedback control and quantum error correction techniques to suppress noise propagation and extend coherence times. Unlike existing approaches primarily relying on physical shielding and quantum error correction, this theory offers a more granular and adaptable method for mitigating decoherence, representing a significant advancement in quantum information processing. The theoretical framework is presented, outlining key equations and control parameters, and demonstrating the potential for achieving significantly longer coherence times under controlled noise conditions. This work lays the groundwork for future research into practical implementations of this theory.

I. V. Tulin