# Using spin bias to manipulate and measure quantum spin in quantum dots

**Authors:** Hai-Zhou Lu, Shun-Qing Shen  
**arXiv:** [0804.1249](https://arxiv.org/abs/0804.1249)  
**Date:** 2008-04-08  
**Summary page:** https://www.summarizepaper.com/en/paper/0804.1249v2/

## Key points

- Investigation of manipulation and measurement of quantum spin in a double-quantum-dot system coupled to electrodes
- Utilization of spin-dependent splitting of chemical potentials to manipulate quantum spin in dot 1 using electrical means
- Proposal to weakly couple dot 2 to dot 1 for monitoring without disturbance
- Interesting behavior due to the presence of an exchange interaction between the two dots
- Polarized spin in dot 1 acts as an effective magnetic field and weakly polarizes the spin in nearby dot 2
- Application of a very small bias voltage to dot 2 for nondestructive identification of spin polarization in dot 1
- Analysis of transport through dot 2 allows determination and monitoring of spin polarization in dot 1
- Complete scheme for manipulating and monitoring trapped spins using pure electric approaches in a double-quantum-dot system presented
- Contribution to understanding quantum spins and potential applications in quantum information processing and spintronics.

## Summary

In this study, the authors investigate the manipulation and measurement of quantum spin in a double-quantum-dot system coupled to electrodes. They utilize the concept of , which refers to the spin-dependent splitting of chemical potentials, to manipulate the quantum spin in one of the quantum dots (dot 1) using purely electrical means. To monitor the manipulation of the quantum spin in dot 1 without causing any disturbance, the authors propose weakly coupling a second quantum dot (dot 2) to dot 1. The presence of an  between these two dots leads to interesting behavior. The polarized spin in dot 1 acts as an effective magnetic field and weakly polarizes the spin in nearby dot 2. To nondestructively identify the spin polarization in dot 1, a very small  is applied to dot 2. This allows for probing of the  through dot 2. By analyzing this transport, it becomes possible to determine and monitor the spin polarization in dot 1. Overall, this study presents a complete scheme for manipulating and monitoring a trapped  using pure electric approaches in a <kd>double-quantum-dot system</ kd>. The findings contribute to our understanding of quantum spins and offer potential applications in areas such as quantum information processing and spintronics.