我們研究由三個金屬島構成的混合式單電子盒(hybrid single-electron box)的系統，以鋁做為超導金屬島，並藉由氧化鋁所形成的穿隧接面(tunnel junction)連接兩旁由銅形成的一般金屬島。兩個一般金屬島各自電容耦合一個單電子電晶體(single-electron transistor)，觀測這兩個單電子電晶體的電流變化可得知三個金屬島間的電子個數分佈及變化。此外，三個金屬島周圍各有一個電極控制金屬島的電位。我們藉由控制這些電極，操縱電子在金屬島中的傳輸。 「共同穿隧(cotunneling)」這種傳輸機制是混合式單電子電晶體(hybrid single-electron transistor)做為電子旋轉門(single-electron turnstile)的最大誤差來源。研究混合式單電子盒裡的電子「共同穿隧」事件，我們發現測量的共同穿隧率在簡併態時為1Hz，與理論預測之值相符。本實驗幫助我們進一步認識混合式單電子電晶體做為一個電子旋轉門的誤差來源。 ;We study dynamics of charge configuration in a hybrid single-electron box. The box consists of a superconducting (aluminum) island and two normal metal (cooper) islands. The aluminum island connects to two copper islands via two tunnel junctions formed by aluminium oxide. The charge state of the box is inspected using two capacitively coupled single-electron transistors (SETs). Each island has a nearby gate electrode to control the charge configuration of the box. "Cotunneling" is the main error process of hybrid SET as a single-electron turnstile. From the study of charge dynamics in a hybrid single-electron box we find the measured cotunneling rate is as low as 1 Hz at degeneracy and compatible with theoretical estimates. The results help to identify the error rate in a hybrid SET.
