New technologies such as quantum-dot cellular automata (QCA) have been showing some remarkable characteristics that standard complementary-metal-oxide semiconductor (CMOS) in deep sub-micron cannot afford. Modeling systems and designing multiple-valued logic gates with QCA have advantages that facilitate the design of complicated logic circuits. In this paper, we propose a novel creative concept for quaternary QCA (QQCA). The concept has been set in QCASim, the new simulator developed by our team exclusively for QCAs\' quaternary mode. Proposed basic quaternary logic gates such as MIN, MAX, and different types of inverters (SQI, PQI, NQI, and IQI) have been designed and verified by QCASim. This study will exemplify how fast and accurately QCASim works by its handy set of CAD tools. A 1×4 decoder is presented using our proposed main gates. Preference points such as the minimum delay, area, and complexity have been achieved in this work. QQCA main logic gates are compared with quaternary gates based on carbon nanotube field-effect transistor (CNFET). The results show that the proposed design is more efficient in terms of latency and energy consumption.