Quantum Information Science and Technology (QIST) represents a foundational aspect of future industrial technology and requires a national commitment to workforce development. To foster talent in this field, it is essential to promote interest beginning with the secondary education curriculum. Learning experiences are a crucial element of career education, providing students with the information they need to prepare for their future. As the cultivation of talent in the field of quantum information science and technology becomes increasingly important, it is essential to investigate experiences related to quantum learning prior to career education. This study examines the quantum-related learning experiences of 157 second-year students from science high schools through an open-ended questionnaire. The study yielded two main findings. First, students employed diverse approaches, beyond the scientific explanations taught in school, to conceptualize quantum phenomena. These students used historical narratives, examples of quantum applications, and even non-scientific cases to explain quantum concepts. This suggests that students gather information about quantum science from popular science books and mass media in addition to their formal education. Notably, science high school students, having chosen early career paths in science and engineering, show particular interest in cutting-edge scientific topics and have some awareness of quantum information science. Second, students exhibited certain unscientific preconceptions about quantum concepts. Students tend to think of 'quantum' as a particle, explain it as the concept of quantization, or confuse and misuse quantum-related concepts. These findings reveal that science high school students have learning experiences with quantum concepts that extend beyond their formal curriculum, and they hold some unscientific preconceptions not previously identified in the literature. This study offers insights for future research on career development and for designing teaching-learning programs in quantum science.