Quantum Computing with Exciton Qubits in Colloidal Semiconductor Nanocrystals

Abstract

The present work evaluates the feasibility of quantum computing with exciton qubits in coupled colloidal semiconductor nanocrystals (NCs). A strategy for manipulating twoqubit states of colloidal NC hetero-dimers is described. We show that a sequence of laser pulses with the same photon energy can bring excitonic states of a nanocrystal hetero-dimer into entanglement and perform arbitrary qubit rotations (quantum gates). Our simulations of a realistic two-particle assembly of CdSe/CdS core/shell NCs demonstrate that such two-qubit gate operations can be driven by optical parametric oscillators with a theoretical error of 0.1%. A strategy for upscaling two-qubit hetero-dimers to N-qubit exciton gates in semiconductor NC assemblies is discussed.

Coupling Perovskite Quantum Dot Pairs in Solution using a Nanoplasmonic Assembly

“…The magnitude of the RET is unusually large when compared with the strongly confined quantum dots that have been explored in the past, which is intriguing because RET has been proposed as a mechanism to obtain entanglement for quantum information processing applications. 25 In the future, we aim to consider the impact of temperature on the observed spectral shifts, which will require adding cyrogenic capability to our setup so that the temperature can be lowered after trapping is achieved. To first order, RET does not depend on temperature, 46,47 however, more advanced electron-phonon theories predict a renormalization of V F as a function of temperature.…”

“…Before discussing the physical mechanism that may be responsible for this red-shift, let us describe a simple generic model for the energy shift arising from a generalized coupling potential V . Considering two oscillators with energies E 1 and E 2 , the shift from E 1 upon coupling can be calculated as: 25,40…”

“…For quantum applications, RET has been proposed theoretically as a mechanism to achieve quantum computing via colloidal quantum dots. 25 Here we estimate the magnitude of the RET induced shift. The dipole moment is estimated from previously reported values of the emission lifetime.…”

“…For quantum dots that are nominally symmetric and do not allow for electron tunneling, Förster resonant energy transfer (RET) has been considered as a way to achieve coupling between dots, providing a possible avenue towards quantum information processing. 25 In the past, RET has been studied for PQDs of different sizes, where the longer wavelength emission peak is enhanced due to one-directional energy transfer. 26 The bi-directional coupling that arises from just two PQDs that are nominally the same size has not been investigated so far.…”

“…S11 (a,b)), since additional scattering can be captured that may show up on top of the usual formula shown earlier, namely Eq. (25). Fig.…”