Numerical Quantum Dynamics (NQD)

Wolfgang Schweizer

Jincheng Zhang

This paper proposes a novel approach to Quantum Key Distribution (QKD) termed Non-Deterministic Quantum Key Distribution (NQD-QKD). The core claim is that incorporating a mechanism of quantum non-determinism significantly enhances the security of QKD protocols and addresses the inherent "eavesdropper advantage" found in traditional QKD systems. NQD-QKD achieves this by leveraging the inherent randomness within quantum entanglement and employing a multi-faceted approach to key generation that moves beyond reliance on single-measurement probability analysis. Specifically, we introduce a process of multi-evaluation and filtering of quantum measurement results during key generation, coupled with robust noise modeling and control to enhance the resilience of the non-deterministic mechanism. The resulting system presents a more complex and unpredictable key generation process, dramatically increasing the difficulty for an eavesdropper to track information and compromise the key. The theoretical framework and mathematical description of NQD-QKD are presented, providing a foundation for future research and implementation.

Jennifer Ann Hollingsworth, Boaz Lubotzky, Somak Majumder +2 more

Quantum light and in particular single photons have become essential resources for a growing number of quantum applications including quantum computing, quantum key distribution and quantum metrology. Solid-state atomlike systems such as semiconductor quantum dots and color defects in crystals have become the hallmark of highly pure single photon emitters in the past two decades. A particular interest has been developed in nanocrystal quantum dots (NQDs) and color centers in diamond as potential compact room-temperature emitters. There are however several challenges that inhibit the use of such sources in current technologies including low photon extraction efficiency, low emission rates and relatively low single photon purities. In this work we will review our efforts in overcoming these technical difficulties using several complementary methods including designing several nanoantenna devices that enhance the directionality and emission rate of the nanoemitter. In addition, we developed several temporal heralding techniques to overcome the hurdle of low single photon purity in NQDs in an effort to produce a highly pure, bright and efficient single photon source on-chip.

Bernardo A. Huberman

Timothy Lovorn, Akihiko Sekine, Allan H. MacDonald

Kuo Hai, Xuefang Deng, Qiong Chen +1 more

We consider an electron confined in a gated nanowire quantum dot (NQD) with arbitrarily strong spin-orbit coupling (SOC) and weak static magnetic field, and treat the latter as a perturbation to seek the maximal spin-motion entangled states with the exact general solutions of the perturbed equations. From the boundedness and self-consistent conditions of the general solutions we find two corrected energies to any n level of the unperturbed system with ground state n = 0, which are much less than the unperturbed level-difference and corresponds to a spin-orbit qubit. We demonstrate the metastability of the two-level states and the decoherence-averse effect of SOC, and suggest an alternative scheme to perform the qubit control, simply by adjusting the orientation of magnetic field for any fixed SOC. Such a adjustment can lead to the spin flipping of the state vector and the position exchanging of the probability-density wavepackets which can be proposed as the non-Abelian quasiparticles. The results could be directly extended to a weakly coupled array of NQDs for coherently encoding the robust spin-orbit qubits.