{"product_id":"pumpette-single-electron-pump","title":"Pumpette – Single-Electron Pump \/ The Ampere from the Elementary Charge Physics Sticker","description":"\u003cp\u003ePumpette, a goblin gate-sentry of The SI Guard, cranks a tiny portcullis that lets one electron through per turn.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eA single-electron pump is a nanoscale island (a quantum dot or metal island) cut off by tunnel barriers. Its charging energy is large enough that electrons can only cross one at a time (Coulomb blockade). Driving the gates at frequency f moves one electron per cycle, so the current is set by counting.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eI = ef\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eI: current (A)\u003c\/li\u003e\n\u003cli\u003ee: elementary charge, 1.602 176 634 × 10⁻¹⁹ C exactly\u003c\/li\u003e\n\u003cli\u003ef: pumping frequency (Hz)\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eSince 20 May 2019 the ampere is defined by fixing e exactly, replacing the old definition based on the force between two parallel wires. At f = 1 GHz the pump gives about 160 pA.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e Real pumps occasionally miss or add an electron, and their currents are small (picoamps to nanoamps), so error counting matters. A pump is one way to realise the ampere directly; in practice it is also realised with Josephson voltage and quantum Hall resistance standards via Ohm's law.\u003c\/p\u003e\u003ch3\u003eOn the sticker\u003c\/h3\u003e\u003cp\u003ePumpette works the gate crank with one bright electron spark at the bars. Printed text: \u003cstrong\u003ePUMPETTE\u003c\/strong\u003e with the line \u003cstrong\u003eI = ef\u003c\/strong\u003e. Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"2\" × 2\" \/ White","offer_id":50963653984359,"sku":"30100059137381668997","price":4.99,"currency_code":"USD","in_stock":true},{"title":"3\" × 3\" \/ White","offer_id":50963654017127,"sku":"18673683244557795850","price":6.99,"currency_code":"USD","in_stock":true},{"title":"4\" × 4\" \/ White","offer_id":50963654049895,"sku":"63066807414294921054","price":8.99,"currency_code":"USD","in_stock":true},{"title":"6\" × 6\" \/ White","offer_id":50963654082663,"sku":"42371506163155400036","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/17545701575641754762_1200.jpg?v=1793664684","url":"https:\/\/pixelatedphysics.com\/de\/products\/pumpette-single-electron-pump","provider":"Pixelated Physics","version":"1.0","type":"link"}