Second-order coherence of microwave photons emitted by a quantum point contact
Second-order coherence of microwave photons emitted by a quantum point contact
复制标题
量子点接触发射的微波光子的二阶相干性
DOI：
10.1103/physrevb.92.195417
复制
发表时间：
2015
影响因子：
3.7
通讯作者：
D. Otten
中科院分区：
文献类型：
--
作者：
F. Hassler;D. Otten
以概率$T$通过量子点接触（偏置在电压$V_0$）传输的电子的散粒噪声导致波动电流，该波动电流又在微波状态中发射辐射。通过计算只有单个通道对输运有贡献的情况下的Fano因子F，证明了在接近e V0/hbar的有限频率和低温下产生的辐射是非经典的，具有亚泊松统计（F<1）。这种效应的起源是产生辐射的电子的费米性质，它降低了同时发射两个或更多光子的概率。然而，Fano因子作为时间平均量，仅提供关于系统的有限信息。在这里，我们计算了这个辐射源的二阶相干性g^{（2）}（\tau）$。我们发现，由于两个贡献的干涉，双光子过程（导致聚束）是完全没有在零温度为$T=50\，\%$。在低温下，我们发现一个竞争的贡献，由于高斯电流的波动（导致聚束）与一个由于非高斯波动（导致反聚束）。在稍微升高的温度下，非高斯贡献被抑制，而高斯贡献在很大程度上保持与温度无关。我们表明，这两个贡献的竞争导致的二阶相干作为时间的函数的非单调行为。因此，$g^{（2）}（\tau）$在时间$\tau^* \simeq\omega_0 ^{-1}$上获得最小值。接近这个时间，在Fano因子已经高于1的温度下，二阶相干性保持低于1。我们确定现实的实验参数，可用于测试的次泊松性质的辐射。
Shot-noise of electrons that are transmitted with probability $T$ through a quantum point contact (biased at a voltage $V_0$) leads to a fluctuating current that in turn emits radiation in the microwave regime. By calculating the Fano factor $F$ for the case where only a single channel contributes to the transport, it has been shown that the radiation produced at finite frequency $\omega_0$ close to $e V_0/\hbar$ and at low temperatures is nonclassical with sub-Poissonian statistics ($F<1$). The origin of this effect is the fermionic nature of the electrons producing the radiation, which reduces the probability of simultaneous emission of two or more photons. However, the Fano factor, being a time-averaged quantity, offers only limited information about the system. Here, we calculate the second-order coherence $g^{(2)}(\tau)$ for this source of radiation. We show that due to the interference of two contributions, two photon processes (leading to bunching) are completely absent at zero temperature for $T=50\,\%$. At low temperatures, we find a competition of the contribution due to Gaussian current-current fluctuations (leading to bunching) with the one due to non-Gaussian fluctuations (leading to antibunching). At slightly elevated temperatures, the non-Gaussian contribution becomes suppressed whereas the Gaussian contributions remain largely independent of temperature. We show that the competition of the two contributions leads to a nonmonotonic behavior of the second-order coherence as a function of time. As a result, $g^{(2)}(\tau)$ obtains a minimal value for times $\tau^* \simeq \omega_0^{-1}$. Close to this time, the second-order coherence remains below 1 at temperatures where the Fano factor is already above 1. We identify realistic experimental parameters that can be used to test the sub-Poissonian nature of the radiation.
影响因子：
3.7
作者：
C. Emary;C. Poltl;A. Carmele;J. Kabuss;A. Knorr;T. Brandes
通讯作者：
C. Emary;C. Poltl;A. Carmele;J. Kabuss;A. Knorr;T. Brandes